[open-ils-commits] r16278 - trunk/Open-ILS/src/c-apps (scottmk)

svn at svn.open-ils.org svn at svn.open-ils.org
Mon Apr 19 22:33:34 EDT 2010


Author: scottmk
Date: 2010-04-19 22:33:32 -0400 (Mon, 19 Apr 2010)
New Revision: 16278

Added:
   trunk/Open-ILS/src/c-apps/buildSQL.c
   trunk/Open-ILS/src/c-apps/oils_buildq.c
   trunk/Open-ILS/src/c-apps/oils_storedq.c
Modified:
   trunk/Open-ILS/src/c-apps/Makefile.am
   trunk/Open-ILS/src/c-apps/oils_qstore.c
Log:
Implement the .prepare and .sql methods (except ignoring
bind variables).

M    Open-ILS/src/c-apps/oils_qstore.c
A    Open-ILS/src/c-apps/oils_buildq.c
A    Open-ILS/src/c-apps/oils_storedq.c
A    Open-ILS/src/c-apps/buildSQL.c
M    Open-ILS/src/c-apps/Makefile.am


Modified: trunk/Open-ILS/src/c-apps/Makefile.am
===================================================================
--- trunk/Open-ILS/src/c-apps/Makefile.am	2010-04-19 18:28:21 UTC (rev 16277)
+++ trunk/Open-ILS/src/c-apps/Makefile.am	2010-04-20 02:33:32 UTC (rev 16278)
@@ -31,7 +31,7 @@
 oils_cstore_la_LDFLAGS = $(AM_LDFLAGS) -loils_idl -ldbi -ldbdpgsql -loils_utils -module
 oils_cstore_la_DEPENDENCIES = liboils_idl.la liboils_idl.la
 
-oils_qstore_la_SOURCES = oils_qstore.c oils_sql.c
+oils_qstore_la_SOURCES = oils_qstore.c oils_sql.c oils_storedq.c oils_buildq.c buildSQL.c
 oils_qstore_la_LDFLAGS = $(AM_LDFLAGS) -loils_idl -ldbi -ldbdpgsql -loils_utils -module
 oils_qstore_la_DEPENDENCIES = liboils_idl.la liboils_idl.la
 

Added: trunk/Open-ILS/src/c-apps/buildSQL.c
===================================================================
--- trunk/Open-ILS/src/c-apps/buildSQL.c	                        (rev 0)
+++ trunk/Open-ILS/src/c-apps/buildSQL.c	2010-04-20 02:33:32 UTC (rev 16278)
@@ -0,0 +1,581 @@
+/**
+	@file buildSQL.c
+	@brief Translate an abstract representation of a query into an SQL statement.
+*/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <dbi/dbi.h>
+#include "opensrf/utils.h"
+#include "opensrf/string_array.h"
+#include "openils/oils_buildq.h"
+
+static void buildQuery( BuildSQLState* state, StoredQ* query );
+static void buildCombo( BuildSQLState* state, StoredQ* query, const char* type_str );
+static void buildSelect( BuildSQLState* state, StoredQ* query );
+static void buildFrom( BuildSQLState* state, FromRelation* core_from );
+static void buildJoin( BuildSQLState* state, FromRelation* join );
+static void buildSelectList( BuildSQLState* state, SelectItem* item );
+static void buildOrderBy( BuildSQLState* state, OrderItem* ord_list );
+static void buildExpression( BuildSQLState* state, Expression* expr );
+
+static void add_newline( BuildSQLState* state );
+static inline void incr_indent( BuildSQLState* state );
+static inline void decr_indent( BuildSQLState* state );
+
+/**
+	@brief Build an SQL query.
+	@param state Pointer to the query-building context.
+	@param query Pointer to the query to be built.
+	@return Zero if successful, or 1 if not.
+
+	Clear the output buffer, call buildQuery() to do the work, and add a closing semicolon.
+*/
+int buildSQL( BuildSQLState* state, StoredQ* query ) {
+	state->error  = 0;
+	buffer_reset( state->sql );
+	state->indent = 0;
+	buildQuery( state, query );
+	if( ! state->error ) {
+		// Remove the trailing space, if there is one, and add a semicolon.
+		char c = buffer_chomp( state->sql );
+		if( c != ' ' )
+			buffer_add_char( state->sql, c );  // oops, not a space; put it back
+		buffer_add( state->sql, ";\n" );
+	}
+	return state->error;
+}
+
+/**
+	@brief Build an SQL query, appending it to what has been built so far.
+	@param state Pointer to the query-building context.
+	@param query Pointer to the query to be built.
+
+	Look at the query type and branch to the corresponding routine.
+*/
+static void buildQuery( BuildSQLState* state, StoredQ* query ) {
+	if( buffer_length( state->sql ))
+		add_newline( state );
+
+	switch( query->type ) {
+		case QT_SELECT :
+			buildSelect( state, query );
+			break;
+		case QT_UNION :
+			buildCombo( state, query, "UNION" );
+			break;
+		case QT_INTERSECT :
+			buildCombo( state, query, "INTERSECT" );
+			break;
+		case QT_EXCEPT :
+			buildCombo( state, query, "EXCEPT" );
+			break;
+		default :
+			osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+				"Internal error: invalid query type %d in query # %d",
+				query->type, query->id ));
+			state->error = 1;
+			break;
+	}
+}
+
+/**
+	@brief Build a UNION, INTERSECT, or EXCEPT query.
+	@param state Pointer to the query-building context.
+	@param query Pointer to the query to be built.
+	@param type_str The query type, as a string.
+*/
+static void buildCombo( BuildSQLState* state, StoredQ* query, const char* type_str ) {
+
+	QSeq* seq = query->child_list;
+	if( !seq ) {
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Internal error: No child queries within %s query # %d",
+			type_str, query->id ));
+		state->error = 1;
+		return;
+	}
+
+	// Traverse the list of child queries
+	while( seq ) {
+		buildQuery( state, seq->child_query );
+		if( state->error ) {
+			sqlAddMsg( state, "Unable to build child query # %d within %s query %d",
+				seq->child_query->id, type_str, query->id );
+			return;
+		}
+		seq = seq->next;
+		if( seq ) {
+			add_newline( state );
+			buffer_add( state->sql, type_str );
+			buffer_add_char( state->sql, ' ' );
+			if( query->use_all )
+				buffer_add( state->sql, "ALL " );
+		}
+	}
+
+	return;
+}
+
+/**
+	@brief Build a SELECT statement.
+	@param state Pointer to the query-building context.
+	@param query Pointer to the StoredQ structure that represents the query.
+*/
+static void buildSelect( BuildSQLState* state, StoredQ* query ) {
+
+	FromRelation* from_clause = query->from_clause;
+	if( !from_clause ) {
+		sqlAddMsg( state, "SELECT has no FROM clause in query # %d", query->id );
+		state->error = 1;
+		return;
+	}
+
+	// To do: get SELECT list; just a stub here
+	buffer_add( state->sql, "SELECT" );
+	incr_indent( state );
+	buildSelectList( state, query->select_list );
+	if( state->error ) {
+		sqlAddMsg( state, "Unable to build SELECT list for query # %d", query->id );
+		state->error = 1;
+		return;
+	}
+	decr_indent( state );
+
+	// Build FROM clause, if there is one
+	if( query->from_clause ) {
+		buildFrom( state, query->from_clause );
+		if( state->error ) {
+			sqlAddMsg( state, "Unable to build FROM clause for query # %d", query->id );
+			state->error = 1;
+			return;
+		}
+	}
+
+	// Build WHERE clause, if there is one
+	if( query->where_clause ) {
+		add_newline( state );
+		buffer_add( state->sql, "WHERE" );
+		incr_indent( state );
+		add_newline( state );
+		buildExpression( state, query->where_clause );
+		if( state->error ) {
+			sqlAddMsg( state, "Unable to build WHERE clause for query # %d", query->id );
+			state->error = 1;
+			return;
+		}
+		//else
+			//buffer_add_char( state->sql, ' ' );
+		decr_indent( state );
+	}
+
+	// Build WHERE clause, if there is one
+	if( query->order_by_list ) {
+		buildOrderBy( state, query->order_by_list );
+		if( state->error ) {
+			sqlAddMsg( state, "Unable to build ORDER BY clause for query # %d", query->id );
+			state->error = 1;
+			return;
+		}
+	}
+	
+	state->error = 0;
+}
+
+/**
+	@brief Build a FROM clause.
+	@param Pointer to the query-building context.
+	@param Pointer to the StoredQ query to which the FROM clause belongs.
+*/
+static void buildFrom( BuildSQLState* state, FromRelation* core_from ) {
+
+	add_newline( state );
+	buffer_add( state->sql, "FROM" );
+	incr_indent( state );
+	add_newline( state );
+
+	switch( core_from->type ) {
+		case FRT_RELATION :
+			if( ! core_from->table_name ) {
+				// To do: if class is available, look up table name
+				// or source_definition in the IDL
+				sqlAddMsg( state, "No table or view name available for core relation # %d",
+					core_from->id );
+				state->error = 1;
+				return;
+			}
+
+			// Add table or view
+			buffer_add( state->sql, core_from->table_name );
+			break;
+		case FRT_SUBQUERY :
+			buffer_add_char( state->sql, '(' );
+			incr_indent( state );
+			buildQuery( state, core_from->subquery );
+			decr_indent( state );
+			add_newline( state );
+			buffer_add_char( state->sql, ')' );
+			break;
+		case FRT_FUNCTION :
+			sqlAddMsg( state, "Functions in FROM clause not yet supported" );
+			state->error = 1;
+			return;
+	}
+
+	// Add a table alias, if possible
+	if( core_from->table_alias ) {
+		buffer_add( state->sql, " AS \"" );
+		buffer_add( state->sql, core_from->table_alias );
+		buffer_add( state->sql, "\" " );
+	}
+	else if( core_from->class_name ) {
+		buffer_add( state->sql, " AS \"" );
+		buffer_add( state->sql, core_from->class_name );
+		buffer_add( state->sql, "\" " );
+	} else
+		buffer_add_char( state->sql, ' ' );
+
+	incr_indent( state );
+	FromRelation* join = core_from->join_list;
+	while( join ) {
+		buildJoin( state, join );
+		if( state->error ) {
+			sqlAddMsg( state, "Unable to build JOIN clause(s) for relation # %d",
+				core_from->id );
+			break;
+		} else
+			join = join->next;
+	}
+	decr_indent( state );
+	decr_indent( state );
+}
+
+static void buildJoin( BuildSQLState* state, FromRelation* join ) {
+	add_newline( state );
+	switch( join->join_type ) {
+		case JT_NONE :
+			sqlAddMsg( state, "Non-join relation # %d in JOIN clause", join->id );
+			state->error = 1;
+			return;
+		case JT_INNER :
+			buffer_add( state->sql, "INNER JOIN " );
+			break;
+		case JT_LEFT:
+			buffer_add( state->sql, "LEFT JOIN " );
+			break;
+		case JT_RIGHT:
+			buffer_add( state->sql, "RIGHT JOIN " );
+			break;
+		case JT_FULL:
+			buffer_add( state->sql, "FULL JOIN " );
+			break;
+		default :
+			sqlAddMsg( state, "Unrecognized join type in relation # %d", join->id );
+			state->error = 1;
+			return;
+	}
+
+	switch( join->type ) {
+		case FRT_RELATION :
+			// Sanity check
+			if( !join->table_name || ! *join->table_name ) {
+				sqlAddMsg( state, "No relation designated for relation # %d", join->id );
+				state->error = 1;
+				return;
+			}
+			buffer_add( state->sql, join->table_name );
+			break;
+		case FRT_SUBQUERY :
+			// Sanity check
+			if( !join->subquery ) {
+				sqlAddMsg( state, "Subquery expected, not found for relation # %d", join->id );
+				state->error = 1;
+				return;
+			} else if( !join->table_alias ) {
+				sqlAddMsg( state, "No table alias for subquery in FROM relation # %d",
+					join->id );
+				state->error = 1;
+				return;
+			}
+			buffer_add_char( state->sql, '(' );
+			incr_indent( state );
+			buildQuery( state, join->subquery );
+			decr_indent( state );
+			add_newline( state );
+			buffer_add_char( state->sql, ')' );
+			break;
+		case FRT_FUNCTION :
+			if( !join->table_name || ! *join->table_name ) {
+				sqlAddMsg( state, "Joins to functions not yet supported in relation # %d",
+					join->id );
+				state->error = 1;
+				return;
+			}
+			break;
+	}
+
+	const char* effective_alias = join->table_alias;
+	if( !effective_alias )
+		effective_alias = join->class_name;
+
+	if( effective_alias ) {
+		buffer_add( state->sql, " AS \"" );
+		buffer_add( state->sql, effective_alias );
+		buffer_add_char( state->sql, '\"' );
+	}
+	
+	if( join->on_clause ) {
+		incr_indent( state );
+		add_newline( state );
+		buffer_add( state->sql, "ON " );
+		buildExpression( state, join->on_clause );
+		decr_indent( state );
+	}
+
+	FromRelation* subjoin = join->join_list;
+	while( subjoin ) {
+		buildJoin( state, subjoin );
+		if( state->error ) {
+			sqlAddMsg( state, "Unable to build JOIN clause(s) for relation # %d", join->id );
+			break;
+		} else
+			subjoin = subjoin->next;
+	}
+}
+
+static void buildSelectList( BuildSQLState* state, SelectItem* item ) {
+	
+	int first = 1;
+	while( item ) {
+		if( !first )
+			buffer_add_char( state->sql, ',' );
+		add_newline( state );
+		buildExpression( state, item->expression );
+		if( state->error ) {
+			sqlAddMsg( state, "Unable to build an expression for SELECT item # %d", item->id );
+			state->error = 1;
+			break;
+		}
+
+		if( item->column_alias ) {
+			buffer_add( state->sql, " AS \"" );
+			buffer_add( state->sql, item->column_alias );
+			buffer_add_char( state->sql, '\"' );
+		}
+		first = 0;
+		item = item->next;
+	};
+	buffer_add_char( state->sql, ' ' );
+}
+
+/**
+	@brief Add an ORDER BY clause to the current query.
+	@param state Pointer to the query-building context.
+	@param ord_list Pointer to the first node in a linked list of OrderItems.
+*/
+static void buildOrderBy( BuildSQLState* state, OrderItem* ord_list ) {
+	add_newline( state );
+	buffer_add( state->sql, "ORDER BY" );
+	incr_indent( state );
+
+	int first = 1;    // boolean
+	while( ord_list ) {
+		if( first )
+			first = 0;
+		else
+			buffer_add_char( state->sql, ',' );
+		add_newline( state );
+		buildExpression( state, ord_list->expression );
+		if( state->error ) {
+			sqlAddMsg( state, "Unable to add ORDER BY expression # %d", ord_list->id );
+			return;
+		}
+
+		ord_list = ord_list->next;
+	}
+
+	decr_indent( state );
+	return;
+}
+
+/**
+	@brief Build an arbitrary expression.
+	@param state Pointer to the query-building context.
+	@param expr Pointer to the Expression representing the expression to be built.
+*/
+static void buildExpression( BuildSQLState* state, Expression* expr ) {
+	if( !expr ) {
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Internal error: NULL pointer to Expression" ));
+		state->error = 1;
+		return;
+	}
+
+	if( expr->parenthesize )
+		buffer_add_char( state->sql, '(' );
+
+	switch( expr->type ) {
+		case EXP_BETWEEN :
+			sqlAddMsg( state, "BETWEEN expressions not yet supported" );
+			state->error = 1;
+			break;
+		case EXP_BOOL :
+			if( expr->literal ) {
+				buffer_add( state->sql, expr->literal );
+				buffer_add_char( state->sql, ' ' );
+			} else
+				buffer_add( state->sql, "FALSE " );
+			break;
+		case EXP_CASE :
+			sqlAddMsg( state, "CASE expressions not yet supported" );
+			state->error = 1;
+			break;
+			case EXP_CAST :                   // Type cast
+			sqlAddMsg( state, "Cast expressions not yet supported" );
+			state->error = 1;
+			break;
+		case EXP_COLUMN :                 // Table column
+			if( expr->table_alias ) {
+				buffer_add_char( state->sql, '\"' );
+				buffer_add( state->sql, expr->table_alias );
+				buffer_add( state->sql, "\"." );
+			}
+			if( expr->column_name ) {
+				buffer_add( state->sql, expr->column_name );
+			} else {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Column name not present in expression # %d", expr->id ));
+				state->error = 1;
+			}
+			break;
+		case EXP_EXIST :
+			if( !expr->subquery ) {
+				osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+					"No subquery found for EXIST expression # %d", expr->id ));
+				state->error = 1;
+			} else {
+				buffer_add( state->sql, "EXISTS (" );
+				incr_indent( state );
+				buildQuery( state, expr->subquery );
+				decr_indent( state );
+				add_newline( state );
+				buffer_add_char( state->sql, ')' );
+			}
+			break;
+		case EXP_FIELD :
+		case EXP_FUNCTION :
+			sqlAddMsg( state, "Expression type not yet supported" );
+			state->error = 1;
+			break;
+		case EXP_IN :
+			if( expr->left_operand ) {
+				buildExpression( state, expr->left_operand );
+				if( !state->error ) {
+					if( expr->subquery ) {
+						buffer_add( state->sql, " IN (" );
+						incr_indent( state );
+						buildQuery( state, expr->subquery );
+						decr_indent( state );
+						add_newline( state );
+						buffer_add_char( state->sql, ')' );
+					} else {
+						sqlAddMsg( state, "IN lists not yet supported" );
+						state->error = 1;
+					}
+				}
+			}
+			break;
+		case EXP_NOT_BETWEEN :
+		case EXP_NOT_EXIST :
+		case EXP_NOT_IN :
+			sqlAddMsg( state, "Expression type not yet supported" );
+			state->error = 1;
+			break;
+		case EXP_NULL :
+			buffer_add( state->sql, "NULL" );
+			break;
+		case EXP_NUMBER :                    // Numeric literal
+			if( !expr->literal ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Internal error: No numeric value in string expression # %d", expr->id ));
+				state->error = 1;
+			} else {
+				buffer_add( state->sql, expr->literal );
+			}
+			break;
+		case EXP_OPERATOR :
+			if( expr->left_operand ) {
+				buildExpression( state, expr->left_operand );
+				if( state->error ) {
+					sqlAddMsg( state, "Unable to emit left operand in expression # %d",
+						expr->id );
+					break;
+				}
+			}
+			buffer_add_char( state->sql, ' ' );
+			buffer_add( state->sql, expr->op );
+			buffer_add_char( state->sql, ' ' );
+			if( expr->right_operand ) {
+				buildExpression( state, expr->right_operand );
+				if( state->error ) {
+					sqlAddMsg( state, "Unable to emit right operand in expression # %d",
+							   expr->id );
+					break;
+				}
+			}
+			break;
+		case EXP_STRING :                     // String literal
+			if( !expr->literal ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Internal error: No string value in string expression # %d", expr->id ));
+					state->error = 1;
+			} else {
+				buffer_add_char( state->sql, '\'' );
+				buffer_add( state->sql, expr->literal );
+				buffer_add_char( state->sql, '\'' );
+			}
+			break;
+		case EXP_SUBQUERY :
+			if( expr->subquery ) {
+				buffer_add_char( state->sql, '(' );
+				incr_indent( state );
+				buildQuery( state, expr->subquery );
+				decr_indent( state );
+				add_newline( state );
+				buffer_add_char( state->sql, ')' );
+			} else {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Internal error: No subquery in subquery expression # %d", expr->id ));
+				state->error = 1;
+			}
+			break;
+	}
+	
+	if( expr->parenthesize )
+		buffer_add_char( state->sql, ')' );
+}
+
+static void add_newline( BuildSQLState* state ) {
+	buffer_add_char( state->sql, '\n' );
+
+	// Add indentation
+	static const char blanks[] = "                                ";   // 32 blanks
+	static const size_t maxlen = sizeof( blanks ) - 1;
+	const int blanks_per_level = 3;
+	int n = state->indent * blanks_per_level;
+	while( n > 0 ) {
+		size_t len = n >= maxlen ? maxlen : n;
+		buffer_add_n( state->sql, blanks, len );
+		n -= len;
+	}
+}
+
+static inline void incr_indent( BuildSQLState* state ) {
+	++state->indent;
+}
+
+static inline void decr_indent( BuildSQLState* state ) {
+	if( state->indent )
+		--state->indent;
+}

Added: trunk/Open-ILS/src/c-apps/oils_buildq.c
===================================================================
--- trunk/Open-ILS/src/c-apps/oils_buildq.c	                        (rev 0)
+++ trunk/Open-ILS/src/c-apps/oils_buildq.c	2010-04-20 02:33:32 UTC (rev 16278)
@@ -0,0 +1,73 @@
+/**
+	@file buildquery.c
+	@brief Routines for maintaining a BuildSQLState.
+
+	A BuildSQLState shuttles information from the routines that load an abstract representation
+	of a query to the routines that build an SQL statement.
+*/
+
+#include <stdlib.h>
+#include <string.h>
+#include <dbi/dbi.h>
+#include "opensrf/utils.h"
+#include "opensrf/log.h"
+#include "opensrf/string_array.h"
+#include "openils/oils_buildq.h"
+
+/**
+	@brief Construct a new BuildSQLState.
+	@param dbhandle Handle for the database connection.
+	@return Pointer to the newly constructed BuildSQLState.
+
+	The calling code is responsible for freeing the BuildSQLState by calling BuildSQLStateFree().
+*/
+BuildSQLState* buildSQLStateNew( dbi_conn dbhandle ) {
+
+	BuildSQLState* state = safe_malloc( sizeof( BuildSQLState ) );
+	state->dbhandle    = dbhandle;
+	state->error       = 0;
+	state->error_msgs  = osrfNewStringArray( 16 );
+	state->sql         = buffer_init( 128 );
+	state->query_stack = NULL;
+	state->expr_stack  = NULL;
+	state->indent      = 0;
+
+	return state;
+}
+
+const char* sqlAddMsg( BuildSQLState* state, const char* msg, ... ) {
+	if( !state || ! state->error_msgs )
+		return "";
+
+	VA_LIST_TO_STRING( msg );
+	osrfStringArrayAdd( state->error_msgs, VA_BUF );
+	return osrfStringArrayGetString( state->error_msgs, state->error_msgs->size - 1 );
+}
+
+/**
+	@brief Free a BuildSQLState.
+	@param state Pointer to the BuildSQLState to be freed.
+
+	We do @em not close the database connection.
+*/
+void buildSQLStateFree( BuildSQLState* state ){
+	
+	if( state ) {
+		osrfStringArrayFree( state->error_msgs );
+		buffer_free( state->sql );
+		while( state->query_stack )
+			pop_id( &state->query_stack );
+		while( state->expr_stack )
+			pop_id( &state->expr_stack );
+		while( state->from_stack )
+			pop_id( &state->from_stack );
+		free( state );
+	}
+}
+
+/**
+	@brief Free up any resources held by the BuildSQL module.
+*/
+void buildSQLCleanup( void ) {
+	storedQCleanup();
+}

Modified: trunk/Open-ILS/src/c-apps/oils_qstore.c
===================================================================
--- trunk/Open-ILS/src/c-apps/oils_qstore.c	2010-04-19 18:28:21 UTC (rev 16277)
+++ trunk/Open-ILS/src/c-apps/oils_qstore.c	2010-04-20 02:33:32 UTC (rev 16278)
@@ -23,8 +23,8 @@
 	has prepared.
 */
 typedef struct {
-	StoredQ*    query;
-	jsonObject* bind_map;
+	BuildSQLState* state;
+	StoredQ*       query;
 } CachedQuery;
 
 static dbi_conn dbhandle; /* our db connection */
@@ -35,7 +35,8 @@
 int doExecute( osrfMethodContext* ctx );
 int doSql( osrfMethodContext* ctx );
 
-static const char* save_query( osrfMethodContext* ctx, StoredQ* query, jsonObject* bind_map );
+static const char* save_query( 
+	osrfMethodContext* ctx, BuildSQLState* state, StoredQ* query );
 static void free_cached_query( char* key, void* data );
 static void userDataFree( void* blob );
 static CachedQuery* search_token( osrfMethodContext* ctx, const char* token );
@@ -206,13 +207,19 @@
 		return -1;
 	}
 
-	osrfLogInfo( OSRF_LOG_MARK, "Building query for id # %d", query_id );
+	osrfLogInfo( OSRF_LOG_MARK, "Loading query for id # %d", query_id );
 
-	// To do: prepare query
-	StoredQ* query = NULL;
-	jsonObject* bind_map = NULL;
-	const char* token = save_query( ctx, query, bind_map );
+	BuildSQLState* state = buildSQLStateNew( dbhandle );
+	StoredQ* query = getStoredQuery( state, query_id );
+	if( state->error ) {
+		osrfLogWarning( OSRF_LOG_MARK, "Unable to load stored query # %d", query_id );
+		osrfAppSessionStatus( ctx->session, OSRF_STATUS_BADREQUEST, "osrfMethodException",
+			ctx->request, "Unable to load stored query" );
+		return -1;
+	}
 
+	const char* token = save_query( ctx, state, query );
+
 	osrfLogInfo( OSRF_LOG_MARK, "Token for query id # %d is \"%s\"", query_id, token );
 
 	osrfAppRespondComplete( ctx, jsonNewObject( token ));
@@ -301,16 +308,37 @@
 	}
 
 	osrfLogInfo( OSRF_LOG_MARK, "Returning SQL for token \"%s\"", token );
+	if( query->state->error ) {
+		osrfLogWarning( OSRF_LOG_MARK, "No valid prepared query available for query id # %d",
+			query->query->id );
+		osrfAppSessionStatus( ctx->session, OSRF_STATUS_BADREQUEST, "osrfMethodException",
+			ctx->request, "No valid prepared query available" );
+		return -1;
+	} else if( buildSQL( query->state, query->query )) {
+		osrfLogWarning( OSRF_LOG_MARK, "Unable to build SQL statement for query id # %d",
+			query->query->id );
+		osrfAppSessionStatus( ctx->session, OSRF_STATUS_BADREQUEST, "osrfMethodException",
+			ctx->request, "Unable to build SQL statement" );
+		return -1;
+	}
 
-	osrfAppRespondComplete( ctx, jsonNewObject( "sql method not yet implemented" ));
+	osrfAppRespondComplete( ctx, jsonNewObject( OSRF_BUFFER_C_STR( query->state->sql )));
 	return 0;
 }
 
-static const char* save_query( osrfMethodContext* ctx, StoredQ* query, jsonObject* bind_map ) {
+/**
+	@brief Save a query in session-level userData for reference in future method calls.
+	@param ctx Pointer to the current method context.
+	@param state Pointer to the state of the query.
+	@param query Pointer to the abstract representation of the query.
+	@return Pointer to an identifying token to be returned to the client.
+*/
+static const char* save_query( 
+	osrfMethodContext* ctx, BuildSQLState* state, StoredQ* query ) {
 
 	CachedQuery* cached_query = safe_malloc( sizeof( CachedQuery ));
+	cached_query->state       = state;
 	cached_query->query       = query;
-	cached_query->bind_map    = bind_map;
 
 	// Get the cache.  If we don't have one yet, make one.
 	osrfHash* cache = ctx->session->userData;
@@ -337,9 +365,8 @@
 static void free_cached_query( char* key, void* data ) {
 	if( data ) {
 		CachedQuery* cached_query = data;
-		//storedQFree( cached_query->query );
-		if( cached_query->bind_map )
-			jsonObjectFree( cached_query->bind_map );
+		buildSQLStateFree( cached_query->state );
+		storedQFree( cached_query->query );
 	}
 }
 

Added: trunk/Open-ILS/src/c-apps/oils_storedq.c
===================================================================
--- trunk/Open-ILS/src/c-apps/oils_storedq.c	                        (rev 0)
+++ trunk/Open-ILS/src/c-apps/oils_storedq.c	2010-04-20 02:33:32 UTC (rev 16278)
@@ -0,0 +1,1357 @@
+/**
+	@file oils_storedq.c
+	@brief Load an abstract representation of a query from the database.
+*/
+
+#include <stdlib.h>
+#include <string.h>
+#include <dbi/dbi.h>
+#include "opensrf/utils.h"
+#include "opensrf/log.h"
+#include "opensrf/string_array.h"
+#include "openils/oils_buildq.h"
+
+#define PRINT if( verbose ) printf
+
+struct IdNode_ {
+	IdNode* next;
+	int id;
+	char* alias;
+};
+
+static int oils_result_get_bool_idx( dbi_result result, int i );
+
+static FromRelation* getFromRelation( BuildSQLState* state, int id );
+static FromRelation* constructFromRelation( BuildSQLState* state, dbi_result result );
+static FromRelation* getJoinList( BuildSQLState* state, int id );
+static void joinListFree( FromRelation* join_list );
+static void fromRelationFree( FromRelation* fr );
+
+static QSeq* loadChildQueries( BuildSQLState* state, int parent_id, const char* type_str );
+static QSeq* constructQSeq( BuildSQLState* state, dbi_result result );
+static void freeQSeqList( QSeq* seq );
+static StoredQ* constructStoredQ( BuildSQLState* state, dbi_result result );
+
+static SelectItem* getSelectList( BuildSQLState* state, int query_id );
+static SelectItem* constructSelectItem( BuildSQLState* state, dbi_result result );
+static void selectListFree( SelectItem* sel );
+
+static Expression* getExpression( BuildSQLState* state, int id );
+static Expression* constructExpression( BuildSQLState* state, dbi_result result );
+static void expressionFree( Expression* exp );
+
+static OrderItem* getOrderByList( BuildSQLState* state, int query_id );
+static OrderItem* constructOrderItem( BuildSQLState* state, dbi_result result );
+static void orderItemListFree( OrderItem* ord );
+
+static void push_id( IdNode** stack, int id, const char* alias );
+static const IdNode* searchIdStack( const IdNode* stack, int id, const char* alias );
+
+// A series of free lists to store already-allocated objects that are not in use, for
+// potential reuse.  This is a hack to reduce churning through malloc() and free().
+static StoredQ* free_storedq_list = NULL;
+static FromRelation* free_from_relation_list = NULL;
+static SelectItem* free_select_item_list = NULL;
+static Expression* free_expression_list = NULL;
+static IdNode* free_id_node_list = NULL;
+static QSeq* free_qseq_list = NULL;
+static OrderItem* free_order_item_list = NULL;
+
+// Boolean; settable by call to oilsStoredQSetVerbose(), used by PRINT macro.
+// The idea is to allow debugging messages from a command line test driver for ease of
+// testing and development, but not from a real server, where messages to stdout don't
+// go anywhere.
+static int verbose = 0;
+
+/**
+	@brief Load a stored query.
+	@param state Pointer to the query-building context.
+	@param query_id ID of the query in query.stored_query.
+	@return A pointer to the newly loaded StoredQ if successful, or NULL if not.
+
+	The calling code is responsible for freeing the StoredQ by calling storedQFree().
+*/
+StoredQ* getStoredQuery( BuildSQLState* state, int query_id ) {
+	if( !state )
+		return NULL;
+
+	// Check the stack to see if the current query is nested inside itself.  If it is, then
+	// abort in order to avoid infinite recursion.  If it isn't, then add it to the stack.
+	// (Make sure to pop it off the stack before returning.)
+	if( searchIdStack( state->query_stack, query_id, NULL )) {
+		osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Infinite recursion detected; query # %d is nested within itself", query_id ));
+		state->error = 1;
+		return NULL;
+	} else
+		push_id( &state->query_stack, query_id, NULL );
+
+	StoredQ* sq = NULL;
+	dbi_result result = dbi_conn_queryf( state->dbhandle,
+		"SELECT id, type, use_all, use_distinct, from_clause, where_clause, having_clause "
+		"FROM query.stored_query WHERE id = %d;", query_id );
+	if( result ) {
+		if( dbi_result_first_row( result ) ) {
+			sq = constructStoredQ( state, result );
+			if( sq ) {
+				PRINT( "Got a query row\n" );
+				PRINT( "\tid: %d\n", sq->id );
+				PRINT( "\ttype: %d\n", (int) sq->type );
+				PRINT( "\tuse_all: %s\n", sq->use_all ? "true" : "false" );
+				PRINT( "\tuse_distinct: %s\n", sq->use_distinct ? "true" : "false" );
+			} else
+				osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to build a query for id = %d", query_id ));
+		} else {
+			sqlAddMsg( state, "Stored query not found for id %d", query_id );
+		}
+
+		dbi_result_free( result );
+	} else {
+		const char* msg;
+		int errnum = dbi_conn_error( state->dbhandle, &msg );
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state, 
+			"Unable to query query.stored_query table: #%d %s",
+			errnum, msg ? msg : "No description available" ));
+	}
+
+	pop_id( &state->query_stack );
+	return sq;
+}
+
+static StoredQ* constructStoredQ( BuildSQLState* state, dbi_result result ) {
+
+	// Get the column values from the result
+	int id               = dbi_result_get_int_idx( result, 1 );
+	const char* type_str = dbi_result_get_string_idx( result, 2 );
+
+	QueryType type;
+	if( !strcmp( type_str, "SELECT" ))
+		type = QT_SELECT;
+	else if( !strcmp( type_str, "UNION" ))
+		type = QT_UNION;
+	else if( !strcmp( type_str, "INTERSECT" ))
+		type = QT_INTERSECT;
+	else if( !strcmp( type_str, "EXCEPT" ))
+		type = QT_EXCEPT;
+	else {
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Invalid query type \"%s\"", type_str ));
+		return NULL;
+	}
+
+	int use_all             = oils_result_get_bool_idx( result, 3 );
+	int use_distinct        = oils_result_get_bool_idx( result, 4 );
+
+	int from_clause_id;
+	if( dbi_result_field_is_null_idx( result, 5 ) )
+		from_clause_id = -1;
+	else
+		from_clause_id = dbi_result_get_int_idx( result, 5 );
+
+	int where_clause_id;
+	if( dbi_result_field_is_null_idx( result, 6 ) )
+		where_clause_id = -1;
+	else
+		where_clause_id = dbi_result_get_int_idx( result, 6 );
+
+	int having_clause_id;
+	if( dbi_result_field_is_null_idx( result, 7 ) )
+		having_clause_id = -1;
+	else
+		having_clause_id = dbi_result_get_int_idx( result, 7 );
+
+	FromRelation* from_clause = NULL;
+	if( QT_SELECT == type ) {
+		// A SELECT query needs a FROM clause; go get it
+		if( from_clause_id != -1 ) {
+			from_clause = getFromRelation( state, from_clause_id );
+			if( !from_clause ) {
+				osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to construct FROM clause for id = %d", from_clause_id ));
+				return NULL;
+			}
+		}
+	} else {
+		// Must be one of UNION, INTERSECT, or EXCEPT
+		if( from_clause_id != -1 )
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"FROM clause found and ignored for %s query in query #%d", type_str, id ));
+	}
+
+	// If this is a SELECT query, we need a SELECT list.  Go get one.
+	SelectItem* select_list = NULL;
+	QSeq* child_list = NULL;
+	if( QT_SELECT == type ) {
+		select_list = getSelectList( state, id );
+		if( !select_list ) {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"No SELECT list found for query id = %d", id ));
+			fromRelationFree( from_clause );
+			return NULL;
+		}
+	} else {
+		// Construct child queries of UNION, INTERSECT, or EXCEPT query
+		child_list = loadChildQueries( state, id, type_str );
+		if( !child_list ) {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"Unable to load child queries for %s query # %d", type_str, id ));
+			state->error = 1;
+			fromRelationFree( from_clause );
+			return NULL;
+		}
+	}
+
+	// Get the WHERE clause, if there is one
+	Expression* where_clause = NULL;
+	if( where_clause_id != -1 ) {
+		where_clause = getExpression( state, where_clause_id );
+		if( ! where_clause ) {
+			// shouldn't happen due to foreign key constraint
+			osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+				"Unable to fetch WHERE expression for query id = %d", id ));
+			freeQSeqList( child_list );
+			fromRelationFree( from_clause );
+			selectListFree( select_list );
+			return NULL;
+		}
+	}
+
+	// Get the ORDER BY clause, if there is one
+	OrderItem* order_by_list = getOrderByList( state, id );
+	if( state->error ) {
+		osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to load ORDER BY clause for query %d", id ));
+		expressionFree( where_clause );
+		freeQSeqList( child_list );
+		fromRelationFree( from_clause );
+		selectListFree( select_list );
+		return NULL;
+	}
+	
+	// Allocate a StoredQ: from the free list if possible, from the heap if necessary
+
+	StoredQ* sq;
+	if( free_storedq_list ) {
+		sq = free_storedq_list;
+		free_storedq_list = free_storedq_list->next;
+	} else
+		sq = safe_malloc( sizeof( StoredQ ) );
+
+	// Populate the StoredQ
+	sq->next = NULL;
+	sq->id = id;
+
+	sq->type = type;
+	sq->use_all = use_all;
+	sq->use_distinct = use_distinct;
+	sq->from_clause = from_clause;
+	sq->where_clause = where_clause;
+	sq->select_list = select_list;
+	sq->child_list = child_list;
+	sq->order_by_list = order_by_list;
+
+	return sq;
+}
+
+/**
+	@brief Load the child queries subordinate to a UNION, INTERSECT, or EXCEPT query.
+	@param state Pointer to the query-building context.
+	@param parent ID of the UNION, INTERSECT, or EXCEPT query.
+	@param type_str The type of the query ("UNION", "INTERSECT", or "EXCEPT").
+	@return If successful, a pointer to a linked list of QSeq, each bearing a pointer to a
+		StoredQ; otherwise NULL.
+
+	The @a type_str parameter is used only for building error messages.
+*/
+static QSeq* loadChildQueries( BuildSQLState* state, int parent_id, const char* type_str ) {
+	QSeq* child_list = NULL;
+	
+	// The ORDER BY is in descending order so that we can build the list by adding to
+	// the head, and it will wind up in the right order.
+	dbi_result result = dbi_conn_queryf( state->dbhandle,
+		"SELECT id, parent_query, seq_no, child_query "
+		"FROM query.query_sequence WHERE parent_query = %d ORDER BY seq_no DESC", parent_id );
+	if( result ) {
+		if( dbi_result_first_row( result ) ) {
+			int count = 0;
+			while( 1 ) {
+				++count;
+				QSeq* seq = constructQSeq( state, result );
+				if( seq ) {
+					PRINT( "Found a child query\n" );
+					PRINT( "\tid: %d\n", seq->id );
+					PRINT( "\tparent id: %d\n", seq->parent_query_id );
+					PRINT( "\tseq_no: %d\n", seq->seq_no );
+					// Add to the head of the list
+					seq->next = child_list;
+					child_list = seq;
+				} else{
+					freeQSeqList( child_list );
+					return NULL;
+				}
+				if( !dbi_result_next_row( result ))
+					break;
+			}
+			if( count < 2 ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"%s query # %d has only one child query", type_str, parent_id ));
+				state->error = 1;
+				freeQSeqList( child_list );
+				return NULL;
+			}
+		} else {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"%s query # %d has no child queries within it", type_str, parent_id ));
+			state->error = 1;
+			return NULL;
+		}
+	} else {
+		const char* msg;
+		int errnum = dbi_conn_error( state->dbhandle, &msg );
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to query query.query_sequence table: # %d %s",
+			errnum, msg ? msg : "No description available" ));
+		state->error = 1;
+		return NULL;
+	}
+
+	return child_list;
+}
+
+static QSeq* constructQSeq( BuildSQLState* state, dbi_result result ) {
+	int id = dbi_result_get_int_idx( result, 1 );
+	int parent_query_id = dbi_result_get_int_idx( result, 2 );
+	int seq_no = dbi_result_get_int_idx( result, 3 );
+	int child_query_id = dbi_result_get_int_idx( result, 4 );
+
+	StoredQ* child_query = getStoredQuery( state, child_query_id );
+	if( !child_query ) {
+		osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to load child query # %d for parent query %d",
+			child_query_id, parent_query_id ));
+		state->error = 1;
+		return NULL;
+	}
+
+	// Allocate a QSeq; from the free list if possible, from the heap if necessary
+	QSeq* seq = NULL;
+	if( free_qseq_list ) {
+		seq = free_qseq_list;
+		free_qseq_list = free_qseq_list->next;
+	} else
+		seq = safe_malloc( sizeof( QSeq ));
+
+	seq->next            = NULL;
+	seq->id              = id;
+	seq->parent_query_id = parent_query_id;
+	seq->seq_no          = seq_no;
+	seq->child_query     = child_query;
+
+	return seq;
+}
+
+static void freeQSeqList( QSeq* seq ) {
+	if( !seq )
+		return;
+
+	QSeq* first = seq;
+	while( seq ) {
+		storedQFree( seq->child_query );
+		seq->child_query = NULL;
+
+		if( seq->next )
+			seq = seq->next;
+		else {
+			seq->next = free_qseq_list;
+			seq = NULL;
+		}
+	}
+	
+	free_qseq_list = first;
+}
+
+/**
+	@brief Deallocate the memory owned by a StoredQ.
+	@param sq Pointer to the StoredQ to be deallocated.
+*/
+void storedQFree( StoredQ* sq ) {
+	if( sq ) {
+		fromRelationFree( sq->from_clause );
+		sq->from_clause = NULL;
+		selectListFree( sq->select_list );
+		sq->select_list = NULL;
+		expressionFree( sq->where_clause );
+		sq->where_clause = NULL;
+		if( sq->child_list ) {
+			freeQSeqList( sq->child_list );
+			sq->child_list = NULL;
+		}
+		if( sq->order_by_list ) {
+			orderItemListFree( sq->order_by_list );
+			sq->order_by_list = NULL;
+		}
+
+		// Stick the empty husk on the free list for potential reuse
+		sq->next = free_storedq_list;
+		free_storedq_list = sq;
+	}
+}
+
+static FromRelation* getFromRelation( BuildSQLState* state, int id ) {
+	FromRelation* fr = NULL;
+	dbi_result result = dbi_conn_queryf( state->dbhandle,
+		"SELECT id, type, table_name, class_name, subquery, function_call, "
+		"table_alias, parent_relation, seq_no, join_type, on_clause "
+		"FROM query.from_relation WHERE id = %d;", id );
+	if( result ) {
+		if( dbi_result_first_row( result ) ) {
+			fr = constructFromRelation( state, result );
+			if( fr ) {
+				PRINT( "Got a from_relation row\n" );
+				PRINT( "\tid: %d\n", fr->id );
+				PRINT( "\ttype: %d\n", (int) fr->type );
+				PRINT( "\ttable_name: %s\n", fr->table_name ? fr->table_name : "(none)" );
+				PRINT( "\tclass_name: %s\n", fr->class_name ? fr->class_name : "(none)" );
+				PRINT( "\tsubquery_id: %d\n", fr->subquery_id );
+				PRINT( "\tfunction_call_id: %d\n", fr->function_call_id );
+				PRINT( "\ttable_alias: %s\n", fr->table_alias ? fr->table_alias : "(none)" );
+				PRINT( "\tparent_relation_id: %d\n", fr->parent_relation_id );
+				PRINT( "\tseq_no: %d\n", fr->seq_no );
+				PRINT( "\tjoin_type = %d\n", fr->join_type );
+				// Check the stack to see if the current from clause is nested inside itself.
+				// If it is, then abort in order to avoid infinite recursion.  If it isn't,
+				// then add it to the stack.  (Make sure to pop it off the stack before
+				// returning.)
+				const char* effective_alias = fr->table_alias;
+				if( !effective_alias )
+					effective_alias = fr->class_name;
+				const IdNode* node = searchIdStack( state->from_stack, id, effective_alias );
+				if( node ) {
+					if( node->id == id )
+						osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+							"Infinite recursion detected; from clause # %d is nested "
+							"within itself", id ));
+					else
+						osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+							"Conflicting nested table aliases \"%s\" in from clause # %d",
+							effective_alias, node->id ));
+					state->error = 1;
+					return NULL;
+				} else
+					push_id( &state->from_stack, id, effective_alias );
+			} else
+				osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to build a FromRelation for id = %d", id ));
+		} else {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"FROM relation not found for id = %d", id ));
+		}
+		dbi_result_free( result );
+	} else {
+		const char* msg;
+		int errnum = dbi_conn_error( state->dbhandle, &msg );
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to query query.from_relation table: #%d %s",
+			errnum, msg ? msg : "No description available" ));
+	}
+
+	if( fr )
+		pop_id( &state->from_stack );
+
+	return fr;
+}
+
+static FromRelation* constructFromRelation( BuildSQLState* state, dbi_result result ) {
+	// Get the column values from the result
+	int id                  = dbi_result_get_int_idx( result, 1 );
+	const char* type_str    = dbi_result_get_string_idx( result, 2 );
+
+	FromRelationType type;
+	if( !strcmp( type_str, "RELATION" ))
+		type = FRT_RELATION;
+	else if( !strcmp( type_str, "SUBQUERY" ))
+		type = FRT_SUBQUERY;
+	else if( !strcmp( type_str, "FUNCTION" ))
+		type = FRT_FUNCTION;
+	else
+		type = FRT_RELATION;     // shouldn't happen due to database constraint
+
+	const char* table_name  = dbi_result_get_string_idx( result, 3 );
+	const char* class_name  = dbi_result_get_string_idx( result, 4 );
+
+	int subquery_id;
+	if( dbi_result_field_is_null_idx( result, 5 ) )
+		subquery_id          = -1;
+	else
+		subquery_id          = dbi_result_get_int_idx( result, 5 );
+
+	int function_call_id;
+	if( dbi_result_field_is_null_idx( result, 6 ) )
+		function_call_id     = -1;
+	else
+		function_call_id     = dbi_result_get_int_idx( result, 6 );
+
+	const char* table_alias  = dbi_result_get_string_idx( result, 7 );
+
+	int parent_relation_id;
+	if( dbi_result_field_is_null_idx( result, 8 ) )
+		parent_relation_id   = -1;
+	else
+		parent_relation_id   = dbi_result_get_int_idx( result, 8 );
+
+	int seq_no               = dbi_result_get_int_idx( result, 9 );
+
+	JoinType join_type;
+	const char* join_type_str = dbi_result_get_string_idx( result, 10 );
+	if( !join_type_str )
+		join_type = JT_NONE;
+	else if( !strcmp( join_type_str, "INNER" ) )
+		join_type = JT_INNER;
+	else if( !strcmp( join_type_str, "LEFT" ) )
+		join_type = JT_LEFT;
+	else if( !strcmp( join_type_str, "RIGHT" ) )
+		join_type = JT_RIGHT;
+	else if( !strcmp( join_type_str, "FULL" ) )
+		join_type = JT_FULL;
+	else
+		join_type = JT_NONE;     // shouldn't happen due to database constraint
+
+	int on_clause_id;
+	if( dbi_result_field_is_null_idx( result, 11 ) )
+		on_clause_id   = -1;
+	else
+		on_clause_id   = dbi_result_get_int_idx( result, 11 );
+
+	StoredQ* subquery = NULL;
+
+	switch ( type ) {
+		case FRT_RELATION :
+			break;
+		case FRT_SUBQUERY :
+			if( -1 == subquery_id ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Internal error: no subquery specified for FROM relation # %d", id ));
+				state->error = 1;
+				return NULL;
+			}
+			if( ! table_alias ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Subquery needs alias in FROM relation # %d", id ));
+				state->error = 1;
+				return NULL;
+			}
+			subquery = getStoredQuery( state, subquery_id );
+			if( ! subquery ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to load subquery for FROM relation # %d", id ));
+				state->error = 1;
+				return NULL;
+			}
+			break;
+		case FRT_FUNCTION :
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"Functions in FROM clause not yet supported" ));
+			state->error = 1;
+			return NULL;
+	}
+
+	FromRelation* join_list = getJoinList( state, id );
+	if( state->error ) {
+		osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to load join list for FROM relation # %d", id ));
+		return NULL;
+	}
+
+	Expression* on_clause = NULL;
+	if( on_clause_id != -1 ) {
+		on_clause = getExpression( state, on_clause_id );
+		if( !on_clause ) {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"Unable to load ON condition for FROM relation # %d", id ));
+			joinListFree( join_list );
+			return NULL;
+		}
+		else
+			PRINT( "\tGot an ON condition\n" );
+	}
+
+	// Allocate a FromRelation: from the free list if possible, from the heap if necessary
+
+	FromRelation* fr;
+	if( free_from_relation_list ) {
+		fr = free_from_relation_list;
+		free_from_relation_list = free_from_relation_list->next;
+	} else
+		fr = safe_malloc( sizeof( FromRelation ) );
+
+	// Populate the FromRelation
+
+	fr->next = NULL;
+	fr->id = id;
+	fr->type = type;
+	fr->table_name = table_name ? strdup( table_name ) : NULL;
+	fr->class_name = class_name ? strdup( class_name ) : NULL;
+	fr->subquery_id = subquery_id;
+	fr->subquery = subquery;
+	fr->function_call_id = function_call_id;
+	fr->table_alias = table_alias ? strdup( table_alias ) : NULL;
+	fr->parent_relation_id = parent_relation_id;
+	fr->seq_no = seq_no;
+	fr->join_type = join_type;
+	fr->on_clause = on_clause;
+	fr->join_list = join_list;
+
+	return fr;
+}
+
+/**
+	@brief Build a list of joined relations.
+	@param state Pointer to the query-building context.
+	@param id ID of the parent relation.
+	@return A pointer to the first in a linked list of FromRelations, if there are any; or
+		NULL if there aren't any, or in case of an error.
+
+	Look for relations joined directly to the parent relation, and make a list of them.
+*/
+static FromRelation* getJoinList( BuildSQLState* state, int id ) {
+	FromRelation* join_list = NULL;
+	
+	// The ORDER BY is in descending order so that we can build the list by adding to
+	// the head, and it will wind up in the right order.
+	dbi_result result = dbi_conn_queryf( state->dbhandle,
+		"SELECT id, type, table_name, class_name, subquery, function_call, "
+		"table_alias, parent_relation, seq_no, join_type, on_clause "
+		"FROM query.from_relation WHERE parent_relation = %d ORDER BY seq_no DESC", id );
+
+	if( result ) {
+		if( dbi_result_first_row( result ) ) {
+			while( 1 ) {
+				FromRelation* relation = constructFromRelation( state, result );
+				if( relation ) {
+					PRINT( "Found a joined relation\n" );
+					PRINT( "\tjoin_type: %d\n", relation->join_type );
+					PRINT( "\ttable_name: %s\n", relation->table_name );
+					relation->next = join_list;
+					join_list = relation;
+				} else {
+					osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+						"Unable to build join list for from relation id #%d", id ));
+					joinListFree( join_list );
+					join_list = NULL;
+					break;
+				}
+				if( !dbi_result_next_row( result ) )
+					break;
+			};
+		}
+	} else {
+		const char* msg;
+		int errnum = dbi_conn_error( state->dbhandle, &msg );
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to query query.from_relation table for join list: #%d %s",
+			errnum, msg ? msg : "No description available" ));
+	}
+
+	return join_list;
+}
+
+/**
+	@brief Free a list of FromRelations.
+	@param join_list Pointer to the first FromRelation in the list.
+*/
+static void joinListFree( FromRelation* join_list ) {
+	while( join_list ) {
+		FromRelation* temp = join_list->next;
+		fromRelationFree( join_list );
+		join_list = temp;
+	}
+}
+
+/**
+	@brief Deallocate a FromRelation.
+	@param fr Pointer to the FromRelation to be freed.
+
+	Free the strings that the FromRelation owns.  The FromRelation itself goes onto a
+	free list for potential reuse.
+*/
+static void fromRelationFree( FromRelation* fr ) {
+	if( fr ) {
+		free( fr->table_name );
+		fr->table_name = NULL;
+		free( fr->class_name );
+		fr->class_name = NULL;
+		if( fr->subquery ) {
+			storedQFree( fr->subquery );
+			fr->subquery = NULL;
+		}
+		free( fr->table_alias );
+		fr->table_alias = NULL;
+		if( fr->on_clause ) {
+			expressionFree( fr->on_clause );
+			fr->on_clause = NULL;
+		}
+		joinListFree( fr->join_list );
+		fr->join_list = NULL;
+
+		fr->next = free_from_relation_list;
+		free_from_relation_list = fr;
+	}
+}
+
+static SelectItem* getSelectList( BuildSQLState* state, int query_id ) {
+	SelectItem* select_list = NULL;
+
+	// The ORDER BY is in descending order so that we can build the list by adding to
+	// the head, and it will wind up in the right order.
+	dbi_result result = dbi_conn_queryf( state->dbhandle,
+		"SELECT id, stored_query, seq_no, expression, column_alias, grouped_by "
+		"FROM query.select_item WHERE stored_query = %d ORDER BY seq_no DESC", query_id );
+	if( result ) {
+		if( dbi_result_first_row( result ) ) {
+			while( 1 ) {
+				SelectItem* item = constructSelectItem( state, result );
+				if( item ) {
+					PRINT( "Found a SELECT item\n" );
+					PRINT( "\tid: %d\n", item->id );
+					PRINT( "\tstored_query_id: %d\n", item->stored_query_id );
+					PRINT( "\tseq_no: %d\n", item->seq_no );
+					PRINT( "\tcolumn_alias: %s\n",
+							item->column_alias ? item->column_alias : "(none)" );
+					PRINT( "\tgrouped_by: %d\n", item->grouped_by );
+
+					item->next = select_list;
+					select_list = item;
+				} else {
+					osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+						"Unable to build select list for query id #%d", query_id ));
+					selectListFree( select_list );
+					select_list = NULL;
+					break;
+				}
+				if( !dbi_result_next_row( result ) )
+					break;
+			};
+		}
+	} else {
+		const char* msg;
+		int errnum = dbi_conn_error( state->dbhandle, &msg );
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+					  "Unable to query query.select_list table: #%d %s",
+					  errnum, msg ? msg : "No description available" ));
+	}
+
+	return select_list;
+}
+
+static SelectItem* constructSelectItem( BuildSQLState* state, dbi_result result ) {
+
+	// Get the column values
+	int id                   = dbi_result_get_int_idx( result, 1 );
+	int stored_query_id      = dbi_result_get_int_idx( result, 2 );
+	int seq_no               = dbi_result_get_int_idx( result, 3 );
+	int expression_id        = dbi_result_get_int_idx( result, 4 );
+	const char* column_alias = dbi_result_get_string_idx( result, 5 );
+	int grouped_by           = oils_result_get_bool_idx( result, 6 );
+	
+	// Construct an Expression
+	Expression* expression = getExpression( state, expression_id );
+	if( !expression ) {
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to fetch expression for id = %d", expression_id ));
+		return NULL;
+	};
+
+	// Allocate a SelectItem: from the free list if possible, from the heap if necessary
+
+	SelectItem* sel;
+	if( free_select_item_list ) {
+		sel = free_select_item_list;
+		free_select_item_list = free_select_item_list->next;
+	} else
+		sel = safe_malloc( sizeof( SelectItem ) );
+
+	sel->next            = NULL;
+	sel->id              = id;
+	sel->stored_query_id = stored_query_id;
+	sel->seq_no          = seq_no;
+	sel->expression      = expression;
+	sel->column_alias    = column_alias ? strdup( column_alias ) : NULL;
+	sel->grouped_by      = grouped_by;
+
+	return sel;
+}
+
+static void selectListFree( SelectItem* sel ) {
+	if( !sel )
+		return;    // Nothing to free
+
+	SelectItem* first = sel;
+	while( 1 ) {
+		free( sel->column_alias );
+		sel->column_alias = NULL;
+		expressionFree( sel->expression );
+		sel->expression = NULL;
+
+		if( NULL == sel->next ) {
+			sel->next = free_select_item_list;
+			break;
+		} else
+			sel = sel->next;
+	};
+
+	// Transfer the entire list to the free list
+	free_select_item_list = first;
+}
+
+static Expression* getExpression( BuildSQLState* state, int id ) {
+	
+	// Check the stack to see if the current expression is nested inside itself.  If it is,
+	// then abort in order to avoid infinite recursion.  If it isn't, then add it to the
+	// stack.  (Make sure to pop it off the stack before returning.)
+	if( searchIdStack( state->expr_stack, id, NULL )) {
+		osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Infinite recursion detected; expression # %d is nested within itself", id ));
+		state->error = 1;
+		return NULL;
+	} else
+		push_id( &state->expr_stack, id, NULL );
+
+		Expression* exp = NULL;
+	dbi_result result = dbi_conn_queryf( state->dbhandle,
+		"SELECT id, type, parenthesize, parent_expr, seq_no, literal, table_alias, "
+		"column_name, left_operand, operator, right_operand, function_id, subquery, cast_type "
+		"FROM query.expression WHERE id = %d;", id );
+	if( result ) {
+		if( dbi_result_first_row( result ) ) {
+			exp = constructExpression( state, result );
+			if( exp ) {
+				PRINT( "Got an expression\n" );
+				PRINT( "\tid = %d\n", exp->id );
+				PRINT( "\ttype = %d\n", exp->type );
+				PRINT( "\tparenthesize = %d\n", exp->parenthesize );
+				PRINT( "\tcolumn_name = %s\n", exp->column_name ? exp->column_name : "(none)" );
+			} else 
+				osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to construct an Expression for id = %d", id ));
+		}
+	} else {
+		const char* msg;
+		int errnum = dbi_conn_error( state->dbhandle, &msg );
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to query query.expression table: #%d %s",
+			errnum, msg ? msg : "No description available" ));
+	}
+
+	pop_id( &state->expr_stack );
+	return exp;
+}
+
+static Expression* constructExpression( BuildSQLState* state, dbi_result result ) {
+
+	int id = dbi_result_get_int_idx( result, 1 );
+	const char* type_str = dbi_result_get_string_idx( result, 2 );
+	
+	ExprType type;
+	if( !strcmp( type_str, "xbet" ))
+		type = EXP_BETWEEN;
+	else if( !strcmp( type_str, "xbool" ))
+		type = EXP_BOOL;
+	else if( !strcmp( type_str, "xcase" ))
+		type = EXP_CASE;
+	else if( !strcmp( type_str, "xcast" ))
+		type = EXP_CAST;
+	else if( !strcmp( type_str, "xcol" ))
+		type = EXP_COLUMN;
+	else if( !strcmp( type_str, "xex" ))
+		type = EXP_EXIST;
+	else if( !strcmp( type_str, "xfld" ))
+		type = EXP_FIELD;
+	else if( !strcmp( type_str, "xfunc" ))
+		type = EXP_FUNCTION;
+	else if( !strcmp( type_str, "xin" ))
+		type = EXP_IN;
+	else if( !strcmp( type_str, "xnbet" ))
+		type = EXP_NOT_BETWEEN;
+	else if( !strcmp( type_str, "xnex" ))
+		type = EXP_NOT_EXIST;
+	else if( !strcmp( type_str, "xnin" ))
+		type = EXP_NOT_IN;
+	else if( !strcmp( type_str, "xnull" ))
+		type = EXP_NULL;
+	else if( !strcmp( type_str, "xnum" ))
+		type = EXP_NUMBER;
+	else if( !strcmp( type_str, "xop" ))
+		type = EXP_OPERATOR;
+	else if( !strcmp( type_str, "xstr" ))
+		type = EXP_STRING;
+	else if( !strcmp( type_str, "xsubq" ))
+		type = EXP_SUBQUERY;
+	else
+		type = EXP_NULL;     // shouldn't happen due to database constraint
+
+	int parenthesize = oils_result_get_bool_idx( result, 3 );
+
+	int parent_expr_id;
+	if( dbi_result_field_is_null_idx( result, 4 ))
+		parent_expr_id = -1;
+	else
+		parent_expr_id = dbi_result_get_int_idx( result, 4 );
+	
+	int seq_no = dbi_result_get_int_idx( result, 5 );
+	const char* literal = dbi_result_get_string_idx( result, 6 );
+	const char* table_alias = dbi_result_get_string_idx( result, 7 );
+	const char* column_name = dbi_result_get_string_idx( result, 8 );
+
+	int left_operand_id;
+	if( dbi_result_field_is_null_idx( result, 9 ))
+		left_operand_id = -1;
+	else
+		left_operand_id = dbi_result_get_int_idx( result, 9 );
+
+	const char* operator = dbi_result_get_string_idx( result, 10 );
+
+	int right_operand_id;
+	if( dbi_result_field_is_null_idx( result, 11 ))
+		right_operand_id = -1;
+	else
+		right_operand_id = dbi_result_get_int_idx( result, 11 );
+
+	int function_id;
+	if( dbi_result_field_is_null_idx( result, 12 ))
+		function_id = -1;
+	else
+		function_id = dbi_result_get_int_idx( result, 12 );
+
+	int subquery_id;
+	if( dbi_result_field_is_null_idx( result, 13 ))
+		subquery_id = -1;
+	else
+		subquery_id = dbi_result_get_int_idx( result, 13 );
+
+	int cast_type_id;
+	if( dbi_result_field_is_null_idx( result, 14 ))
+		cast_type_id = -1;
+	else
+		cast_type_id = dbi_result_get_int_idx( result, 14 );
+
+	Expression* left_operand = NULL;
+	Expression* right_operand = NULL;
+	StoredQ* subquery = NULL;
+
+	if( EXP_OPERATOR == type ) {
+		// Load left and/or right operands
+		if( -1 == left_operand_id && -1 == right_operand_id ) {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"Expression # %d is an operator with no operands", id ));
+			state->error = 1;
+			return NULL;
+		}
+
+		if( left_operand_id != -1 ) {
+			left_operand = getExpression( state, left_operand_id );
+			if( !left_operand ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to get left operand in expression # %d", id ));
+				state->error = 1;
+				return NULL;
+			}
+		}
+
+		if( right_operand_id != -1 ) {
+			right_operand = getExpression( state, right_operand_id );
+			if( !right_operand ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to get right operand in expression # %d", id ));
+				state->error = 1;
+				expressionFree( left_operand );
+				return NULL;
+			}
+		}
+	} else if( EXP_IN == type ) {
+		if( -1 == left_operand_id ) {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"IN condition has no left operand in expression # %d", id ));
+			state->error = 1;
+			return NULL;
+		} else {
+			left_operand = getExpression( state, left_operand_id );
+			if( !left_operand ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to get left operand for IN condition in expression # %d", id ));
+				state->error = 1;
+				return NULL;
+			}
+		}
+
+		if( -1 == subquery_id ) {
+			// To do: load IN list of subexpressions
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"IN lists not yet supported for expression # %d", id ));
+			state->error = 1;
+			return NULL;
+		} else {
+			subquery = getStoredQuery( state, subquery_id );
+			if( !subquery ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to load subquery for IN expression # %d", id ));
+				state->error = 1;
+				return NULL;
+			}
+		}
+	} else if( EXP_EXIST == type ) {
+		if( -1 == subquery_id ) {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"Internal error: No subquery found for EXIST expression # %d", id ));
+			state->error = 1;
+			return NULL;
+		} else {
+			subquery = getStoredQuery( state, subquery_id );
+			if( !subquery ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to load subquery for EXIST expression # %d", id ));
+				state->error = 1;
+				return NULL;
+			}
+		}
+	} else if( EXP_SUBQUERY == type ) {
+		if( -1 == subquery_id ) {
+			osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+				"Subquery expression # %d has no query id", id ));
+			state->error = 1;
+			return NULL;
+		} else {
+			// Load a subquery, if there is one
+			subquery = getStoredQuery( state, subquery_id );
+			if( !subquery ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Unable to load subquery for expression # %d", id ));
+				state->error = 1;
+				return NULL;
+			}
+			if( subquery->select_list && subquery->select_list->next ) {
+				osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+					"Subquery # %d as expression returns more than one column", subquery_id ));
+				state->error = 1;
+				return NULL;
+			}
+			PRINT( "\tExpression is subquery %d\n", subquery_id );
+		}
+	}
+
+	// Allocate an Expression: from the free list if possible, from the heap if necessary
+	Expression* exp = NULL;
+	if( free_expression_list ) {
+		exp = free_expression_list;
+		free_expression_list = free_expression_list->next;
+	} else
+		exp = safe_malloc( sizeof( Expression ) );
+
+	// Populate the Expression
+	exp->next = NULL;
+	exp->id = id;
+	exp->type = type;
+	exp->parenthesize = parenthesize;
+	exp->parent_expr_id = parent_expr_id;
+	exp->seq_no = seq_no;
+	exp->literal = literal ? strdup( literal ) : NULL;
+	exp->table_alias = table_alias ? strdup( table_alias ) : NULL;
+	exp->column_name = column_name ? strdup( column_name ) : NULL;
+	exp->left_operand = left_operand;
+	exp->op = operator ? strdup( operator ) : NULL;
+	exp->right_operand = right_operand;
+	exp->function_id = function_id;
+	exp->subquery_id = subquery_id;
+	exp->subquery = subquery;
+	exp->cast_type_id = subquery_id;
+
+	return exp;
+}
+
+/**
+	@brief Deallocate an Expression.
+	@param exp Pointer to the Expression to be deallocated.
+
+	Free the strings owned by the Expression.  Put the Expressions itself into a free list.
+*/
+static void expressionFree( Expression* exp ) {
+	if( exp ) {
+		free( exp->literal );
+		exp->literal = NULL;
+		free( exp->table_alias );
+		exp->table_alias = NULL;
+		free( exp->column_name );
+		exp->column_name = NULL;
+		if( exp->left_operand ) {
+			expressionFree( exp->left_operand );
+			exp->left_operand = NULL;
+		}
+		free( exp->op );
+		exp->op = NULL;
+		if( exp->right_operand ) {
+			expressionFree( exp->right_operand );
+			exp->right_operand = NULL;
+		}
+		if( exp->subquery ) {
+			storedQFree( exp->subquery );
+			exp->subquery = NULL;
+		}
+
+		exp->next = free_expression_list;
+		free_expression_list = exp;
+	}
+}
+
+static OrderItem* getOrderByList( BuildSQLState* state, int query_id ) {
+	OrderItem* ord_list = NULL;
+
+	// The ORDER BY is in descending order so that we can build the list by adding to
+	// the head, and it will wind up in the right order.
+	dbi_result result = dbi_conn_queryf( state->dbhandle,
+		"SELECT id, stored_query, seq_no, expression "
+		"FROM query.order_by_item WHERE stored_query = %d ORDER BY seq_no DESC", query_id );
+	if( result ) {
+		if( dbi_result_first_row( result ) ) {
+			while( 1 ) {
+				OrderItem* item = constructOrderItem( state, result );
+				if( item ) {
+					PRINT( "Found an ORDER BY item\n" );
+
+					item->next = ord_list;
+					ord_list = item;
+				} else {
+					osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+						"Unable to build ORDER BY item for query id #%d", query_id ));
+					orderItemListFree( ord_list );
+					ord_list = NULL;
+					break;
+				}
+				if( !dbi_result_next_row( result ) )
+					break;
+			};
+		}
+	}  else {
+		const char* msg;
+		int errnum = dbi_conn_error( state->dbhandle, &msg );
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to query query.order_by_list table: #%d %s",
+			errnum, msg ? msg : "No description available" ));
+	}
+
+	return ord_list;
+}
+
+static OrderItem* constructOrderItem( BuildSQLState* state, dbi_result result ) {
+	int id                   = dbi_result_get_int_idx( result, 1 );
+	int stored_query_id      = dbi_result_get_int_idx( result, 2 );
+	int seq_no               = dbi_result_get_int_idx( result, 3 );
+	int expression_id        = dbi_result_get_int_idx( result, 4 );
+	// Allocate a SelectItem: from the free list if possible, from the heap if necessary
+
+	// Construct an Expression
+	Expression* expression = getExpression( state, expression_id );
+	if( !expression ) {
+		osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+			"Unable to fetch ORDER BY expression for id = %d", expression_id ));
+		return NULL;
+	};
+
+	// Allocate an OrderItem; from the free list if possible, or from the heap if necessary.
+	OrderItem* ord;
+	if( free_order_item_list ) {
+		ord = free_order_item_list;
+		free_order_item_list = free_order_item_list->next;
+	} else
+		ord = safe_malloc( sizeof( OrderItem ));
+
+	ord->next            = NULL;
+	ord->id              = id;
+	ord->stored_query_id = stored_query_id;
+	ord->seq_no          = seq_no;
+	ord->expression      = expression;
+
+	return ord;
+}
+
+/**
+	@brief Deallocate a linked list of OrderItems.
+	@param exp Pointer to the first OrderItem in the list to be deallocated.
+
+	Deallocate the memory owned by the OrderItems.  Put the items themselves into a free list.
+*/
+static void orderItemListFree( OrderItem* ord ) {
+	if( !ord )
+		return;    // Nothing to free
+
+	OrderItem* first = ord;
+	while( 1 ) {
+		expressionFree( ord->expression );
+		ord->expression = NULL;
+
+		if( NULL == ord->next ) {
+			ord->next = free_order_item_list;
+			break;
+		} else
+			ord = ord->next;
+	};
+
+	// Transfer the entire list to the free list
+	free_order_item_list = first;
+}
+
+/**
+	@brief Push an IdNode onto a stack of IdNodes.
+	@param stack Pointer to the stack.
+	@param id Id of the new node.
+	@param alias Alias, if any, of the new node.
+*/
+static void push_id( IdNode** stack, int id, const char* alias ) {
+
+	if( stack ) {
+		// Allocate a node; from the free list if possible, from the heap if necessary.
+		IdNode* node = NULL;
+		if( free_id_node_list ) {
+			node = free_id_node_list;
+			free_id_node_list = free_id_node_list->next;
+		} else
+			node = safe_malloc( sizeof( IdNode ));
+
+		// Populate it
+		node->next = *stack;
+		node->id = id;
+		if( alias )
+			node->alias = strdup( alias );
+		else
+			node->alias = NULL;
+		
+		// Reseat the stack
+		*stack = node;
+	}
+}
+
+/**
+	@brief Remove the node at the top of an IdNode stack.
+	@param stack Pointer to the IdNode stack.
+*/
+void pop_id( IdNode** stack ) {
+	if( stack ) {
+		IdNode* node = *stack;
+		*stack = node->next;
+
+		if( node->alias ) {
+			free( node->alias );
+			node->alias = NULL;
+		}
+
+		node->next = free_id_node_list;
+		free_id_node_list = node;
+	}
+}
+
+/**
+	@brief Search a stack of IDs for a match by either ID or, optionally, by alias.
+	@param stack Pointer to the stack.
+	@param id The id to search for.
+	@param alias (Optional) the alias to search for.
+	@return A pointer to the matching node if one is found, or NULL if not.
+
+	This search is used to detect cases where a query, expression, or FROM clause is nested
+	inside itself, in order to avoid infinite recursion; or in order to avoid conflicting
+	table references in a FROM clause.
+*/
+static const IdNode* searchIdStack( const IdNode* stack, int id, const char* alias ) {
+	if( stack ) {
+		const IdNode* node = stack;
+		while( node ) {
+			if( node->id == id )
+				return node;        // Matched on id
+			else if( alias && node->alias && !strcmp( alias, node->alias ))
+				return node;        // Matched on alias
+			else
+				node = node->next;
+		}
+	}
+	return NULL;   // No match found
+}
+
+/**
+	@brief Free up any resources held by the StoredQ module.
+*/
+void storedQCleanup( void ) {
+
+	// Free all the nodes in the free state list
+	StoredQ* sq = free_storedq_list;
+	while( sq ) {
+		free_storedq_list = sq->next;
+		free( sq );
+		sq = free_storedq_list;
+	}
+
+	// Free all the nodes in the free from_relation list
+	FromRelation* fr = free_from_relation_list;
+	while( fr ) {
+		free_from_relation_list = fr->next;
+		free( fr );
+		fr = free_from_relation_list;
+	}
+
+	// Free all the nodes in the free expression list
+	Expression* exp = free_expression_list;
+	while( exp ) {
+		free_expression_list = exp->next;
+		free( exp );
+		exp = free_expression_list;
+	}
+
+	// Free all the nodes in the free select item list
+	SelectItem* sel = free_select_item_list;
+	while( sel ) {
+		free_select_item_list = sel->next;
+		free( sel );
+		sel = free_select_item_list;
+	}
+
+	// Free all the nodes in the free select item list
+	IdNode* node = free_id_node_list;
+	while( node ) {
+		free_id_node_list = node->next;
+		free( node );
+		node = free_id_node_list;
+	}
+
+	// Free all the nodes in the free query sequence list
+	QSeq* seq = free_qseq_list;
+	while( seq ) {
+		free_qseq_list = seq->next;
+		free( seq );
+		seq = free_qseq_list;
+	}
+
+	// Free all the nodes in the free order item list
+	OrderItem* ord = free_order_item_list;
+	while( ord ) {
+		free_order_item_list = ord->next;
+		free( ord );
+		ord = free_order_item_list;
+	}
+}
+
+/**
+	@brief Return a boolean value from a database result.
+	@param result The database result.
+	@param i Index of the column in the result, starting with 1 );
+	@return 1 if true, or 0 for false.
+
+	Null values and error conditions are interpreted as FALSE.
+*/
+static int oils_result_get_bool_idx( dbi_result result, int i ) {
+	if( result ) {
+		const char* str = dbi_result_get_string_idx( result, i );
+		return (str && *str == 't' ) ? 1 : 0;
+	} else
+		return 0;
+}
+
+void oilsStoredQSetVerbose( void ) {
+	verbose = 1;
+}



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