SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.65 2002/05/30 02:35:12 drh Exp $
*/
#include "sqliteInt.h"


/*
** Construct a new expression node and return a pointer to it.  Memory
** for this node is obtained from sqliteMalloc().  The calling function

      sqliteExprCode(pParse, pExpr->pLeft);
      break;
    }
    case TK_CASE: {
      int expr_end_label;
      int null_result_label;
      int jumpInst;
      int nullBypassInst;
      int addr;
      int nExpr;
      int i;

      assert(pExpr->pList);
      assert((pExpr->pList->nExpr % 2) == 0);
      assert(pExpr->pList->nExpr > 0);
      nExpr = pExpr->pList->nExpr;
      expr_end_label = sqliteVdbeMakeLabel(v);
      null_result_label = sqliteVdbeMakeLabel(v);
      if( pExpr->pLeft ){
        sqliteExprCode(pParse, pExpr->pLeft);
        nullBypassInst = sqliteVdbeAddOp(v, OP_IsNull, -1, 0);
      }
      for(i=0; i<nExpr; i=i+2){
        sqliteExprCode(pParse, pExpr->pList->a[i].pExpr);
        sqliteVdbeAddOp(v, OP_IsNull, -1, null_result_label);
        if( pExpr->pLeft ){
          sqliteVdbeAddOp(v, OP_Dup, 1, 1);
          jumpInst = sqliteVdbeAddOp(v, OP_Ne, 0, 0);

      }else{
        sqliteVdbeAddOp(v, OP_String, 0, 0);
      }
      sqliteVdbeResolveLabel(v, expr_end_label);
      if( pExpr->pLeft ){
        sqliteVdbeAddOp(v, OP_Pull, 1, 0);
        sqliteVdbeAddOp(v, OP_Pop, 1, 0);
        sqliteVdbeChangeP2(v, nullBypassInst, sqliteVdbeCurrentAddr(v));
      }
    }
    break;
  }
}

/*

      sqliteVdbeAddOp(v, OP_Goto, 0, dest);
      sqliteExprCode(pParse, pExpr->pList->a[1].pExpr);
      sqliteVdbeAddOp(v, OP_Gt, jumpIfNull, dest);
      break;
    }
    default: {
      sqliteExprCode(pParse, pExpr);
      sqliteVdbeAddOp(v, OP_IfNot, jumpIfNull, dest);

      break;
    }
  }
}

/*
** Do a deep comparison of two expression trees.  Return TRUE (non-zero)

# 2001 September 15
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing expressions.
#
# $Id: expr.test,v 1.22 2002/05/30 02:35:12 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Create a table to work with.
#
execsql {CREATE TABLE test1(i1 int, i2 int, r1 real, r2 real, t1 text, t2 text)}

	{CASE i1 WHEN 1 THEN 'one' WHEN NULL THEN 'two' ELSE 'error' END} {{}}
test_expr expr-case.8 {i1=3} \
	{CASE i1 WHEN 1 THEN 'one' WHEN NULL THEN 'two' ELSE 'error' END} {{}}
test_expr expr-case.9 {i1=3} \
	{CASE i1 WHEN 1 THEN 'one' WHEN 2 THEN 'two' ELSE 'error' END} error
test_expr expr-case.10 {i1=3} \
	{CASE i1 WHEN 1 THEN 'one' WHEN 2 THEN 'two' END} {{}}
test_expr expr-case.11 {i1=null} \
	{CASE i1 WHEN 1 THEN 'one' WHEN 2 THEN 'two' ELSE 3 END} {{}}
test_expr expr-case.12 {i1=7} \
	{ CASE WHEN i1 < 5 THEN 'low' 
	       WHEN i1 < 10 THEN 'medium' 
               WHEN i1 < 15 THEN 'high' ELSE 'error' END} medium


# The sqliteExprIfFalse and sqliteExprIfTrue routines are only
# executed as part of a WHERE clause.  Create a table suitable