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robertmhaasrobertmhaas
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pgbench: Add a real expression syntax to \set
Previously, you could do \set variable operand1 operator operand2, but nothing more complicated. Now, you can \set variable expression, which makes it much simpler to do multi-step calculations here. This also adds support for the modulo operator (%), with the same semantics as in C. Robert Haas and Fabien Coelho, reviewed by Álvaro Herrera and Stephen Frost
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8 files changed

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‎contrib/pgbench/.gitignore‎

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/exprparse.c
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/exprscan.c
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/pgbench

‎contrib/pgbench/Makefile‎

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@@ -4,7 +4,9 @@ PGFILEDESC = "pgbench - a simple program for running benchmark tests"
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PGAPPICON = win32
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PROGRAM = pgbench
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OBJS = pgbench.o $(WIN32RES)
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OBJS = pgbench.o exprparse.o $(WIN32RES)
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EXTRA_CLEAN = exprparse.c exprscan.c
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PG_CPPFLAGS = -I$(libpq_srcdir)
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PG_LIBS = $(libpq_pgport) $(PTHREAD_LIBS)
@@ -18,8 +20,21 @@ subdir = contrib/pgbench
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top_builddir = ../..
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include $(top_builddir)/src/Makefile.global
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include $(top_srcdir)/contrib/contrib-global.mk
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distprep: exprparse.c exprscan.c
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endif
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ifneq ($(PORTNAME), win32)
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override CFLAGS += $(PTHREAD_CFLAGS)
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endif
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# There is no correct way to write a rule that generates two files.
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# Rules with two targets don't have that meaning, they are merely
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# shorthand for two otherwise separate rules. To be safe for parallel
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# make, we must chain the dependencies like this. The semicolon is
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# important; otherwise, make will choose the built-in rule.
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exprparse.h: exprparse.c ;
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# exprscan is compiled as part of exprparse
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exprparse.o: exprscan.c

‎contrib/pgbench/exprparse.y‎

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%{
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/*-------------------------------------------------------------------------
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*
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* exprparse.y
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* bison grammar for a simple expression syntax
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*
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres_fe.h"
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#include "pgbench.h"
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PgBenchExpr *expr_parse_result;
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static PgBenchExpr *make_integer_constant(int64 ival);
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static PgBenchExpr *make_variable(char *varname);
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static PgBenchExpr *make_op(char operator, PgBenchExpr *lexpr,
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PgBenchExpr *rexpr);
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%}
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%expect 0
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%name-prefix="expr_yy"
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%union
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{
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int64 ival;
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char *str;
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PgBenchExpr *expr;
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}
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%type <expr> expr
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%type <ival> INTEGER
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%type <str> VARIABLE
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%token INTEGER VARIABLE
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%token CHAR_ERROR /* never used, will raise a syntax error */
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%left '+' '-'
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%left '*' '/' '%'
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%right UMINUS
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%%
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result: expr { expr_parse_result = $1; }
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expr: '(' expr ')' { $$ = $2; }
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| '+' expr %prec UMINUS { $$ = $2; }
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| '-' expr %prec UMINUS { $$ = make_op('-', make_integer_constant(0), $2); }
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| expr '+' expr { $$ = make_op('+', $1, $3); }
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| expr '-' expr { $$ = make_op('-', $1, $3); }
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| expr '*' expr { $$ = make_op('*', $1, $3); }
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| expr '/' expr { $$ = make_op('/', $1, $3); }
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| expr '%' expr { $$ = make_op('%', $1, $3); }
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| INTEGER { $$ = make_integer_constant($1); }
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| VARIABLE { $$ = make_variable($1); }
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;
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%%
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static PgBenchExpr *
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make_integer_constant(int64 ival)
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{
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PgBenchExpr *expr = pg_malloc(sizeof(PgBenchExpr));
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expr->etype = ENODE_INTEGER_CONSTANT;
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expr->u.integer_constant.ival = ival;
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return expr;
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}
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static PgBenchExpr *
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make_variable(char *varname)
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{
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PgBenchExpr *expr = pg_malloc(sizeof(PgBenchExpr));
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expr->etype = ENODE_VARIABLE;
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expr->u.variable.varname = varname;
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return expr;
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}
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static PgBenchExpr *
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make_op(char operator, PgBenchExpr *lexpr, PgBenchExpr *rexpr)
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{
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PgBenchExpr *expr = pg_malloc(sizeof(PgBenchExpr));
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expr->etype = ENODE_OPERATOR;
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expr->u.operator.operator = operator;
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expr->u.operator.lexpr = lexpr;
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expr->u.operator.rexpr = rexpr;
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return expr;
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}
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#include "exprscan.c"

‎contrib/pgbench/exprscan.l‎

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%{
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/*-------------------------------------------------------------------------
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*
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* exprscan.l
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* a lexical scanner for a simple expression syntax
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*
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*-------------------------------------------------------------------------
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*/
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/* line and column number for error reporting */
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static int yyline = 0, yycol = 0;
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/* Handles to the buffer that the lexer uses internally */
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static YY_BUFFER_STATE scanbufhandle;
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static char *scanbuf;
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static int scanbuflen;
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/* flex 2.5.4 doesn't bother with a decl for this */
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int expr_yylex(void);
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%}
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%option 8bit
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%option never-interactive
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%option nodefault
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%option noinput
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%option nounput
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%option noyywrap
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%option warn
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%option prefix="expr_yy"
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non_newline [^\n\r]
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space [ \t\r\f]
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%%
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"+" { yycol += yyleng; return '+'; }
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"-" { yycol += yyleng; return '-'; }
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"*" { yycol += yyleng; return '*'; }
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"/" { yycol += yyleng; return '/'; }
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"%" { yycol += yyleng; return '%'; }
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"(" { yycol += yyleng; return '('; }
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")" { yycol += yyleng; return ')'; }
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:[a-zA-Z0-9_]+ { yycol += yyleng; yylval.str = pg_strdup(yytext + 1); return VARIABLE; }
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[0-9]+ { yycol += yyleng; yylval.ival = strtoint64(yytext); return INTEGER; }
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[\n] { yycol = 0; yyline++; }
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{space} { yycol += yyleng; /* ignore */ }
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. {
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yycol += yyleng;
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fprintf(stderr, "unexpected character '%s'\n", yytext);
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return CHAR_ERROR;
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}
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%%
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void
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yyerror(const char *message)
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{
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/* yyline is always 1 as pgbench calls the parser for each line...
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* so the interesting location information is the column number */
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fprintf(stderr, "%s at column %d\n", message, yycol);
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/* go on to raise the error from pgbench with more information */
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/* exit(1); */
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}
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/*
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* Called before any actual parsing is done
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*/
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void
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expr_scanner_init(const char *str)
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{
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Size slen = strlen(str);
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/*
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* Might be left over after error
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*/
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if (YY_CURRENT_BUFFER)
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yy_delete_buffer(YY_CURRENT_BUFFER);
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/*
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* Make a scan buffer with special termination needed by flex.
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*/
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scanbuflen = slen;
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scanbuf = pg_malloc(slen + 2);
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memcpy(scanbuf, str, slen);
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scanbuf[slen] = scanbuf[slen + 1] = YY_END_OF_BUFFER_CHAR;
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scanbufhandle = yy_scan_buffer(scanbuf, slen + 2);
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BEGIN(INITIAL);
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}
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/*
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* Called after parsing is done to clean up after seg_scanner_init()
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*/
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void
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expr_scanner_finish(void)
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{
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yy_delete_buffer(scanbufhandle);
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pg_free(scanbuf);
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}

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