first working version of a query parser.

src/query/build_parser.sh

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+#!/usr/bin/env bash
+
+yacc -t -d query.yacc && lex query.lex && gcc -g *.c

src/query/language.y

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+// -*- go -*-
+
+// definitions
+
+%{
+	import (
+		"fmt"
+	)
+%}
+
+
+// rules
+%union
+{
+	node Node
+}
+%type <node> hello
+%%
+
+hello: 'hello'
+{
+	// whatever
+}
+
+// subroutines
+%%
+type Lexer int
+
+func (self *Lexer) Lex(yylval *query_SymType) int {
+	fmt.Printf("got %v\n", yylval)
+	return 0;
+}
+
+func (self *Lexer) Error(e error) {
+	fmt.Printf("Error: %s\n", err)
+}

src/query/query.lex

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+%{
+#include <stdlib.h>
+#include <string.h>
+#include "query_types.h"
+#include "y.tab.h"
+%}
+
+%option reentrant
+%option bison-bridge
+%option noyywrap
+%%
+
+;                         { return *yytext; }
+from                      { return FROM; }
+where                     { return WHERE; }
+select                    { return SELECT; }
+=                         { return *yytext; }
+[a-zA-Z][a-zA-Z0-9]*      { yylval->string = strdup(yytext); return NAME; }
+[0-9]+                    { yylval->i = atoi(yytext); return INT_VALUE; }
+\'.*\'                    {
+  yytext[yyleng-1] = '\0';
+  yylval->string = strdup(yytext+1);
+  return STRING_VALUE;
+}

src/query/query.yacc

@@ -0,0 +1,106 @@
+%{
+#include <stdio.h>
+#include "query_types.h"
+%}
+
+%union {
+  char *string;
+  int i;
+  from *f;
+  where *w;
+  value *v;
+}
+
+// debugging
+%debug
+
+// declare that we want a reentrant parser
+%define      api.pure
+%parse-param {query *q}
+%parse-param {void *scanner}
+%lex-param   {void *scanner}
+
+%token          SELECT FROM WHERE EQUAL
+%token <string> NAME STRING_VALUE
+%token <i>      INT_VALUE
+
+%type <f>       FROM_CLAUSE
+%type <string>  TABLE_NAME
+%type <string>  FIELD_NAME
+%type <w>       WHERE_CLAUSE
+%type <v>       FIELD_VALUE
+%start          QUERY
+
+%%
+QUERY: SELECT FROM_CLAUSE WHERE_CLAUSE ';'
+{
+  q->f = $2;
+  q->w = $3;
+}
+
+FROM_CLAUSE: FROM TABLE_NAME
+{
+  $$ = malloc(sizeof(from));
+  $$->table = $2;
+}
+
+WHERE_CLAUSE: WHERE FIELD_NAME '=' FIELD_VALUE
+{
+  $$ = malloc(sizeof(where));
+  $$->column_name = $2;
+  $$->op = OP_EQUAL;
+  $$->v = $4;
+}
+
+TABLE_NAME: NAME
+FIELD_NAME: NAME
+{
+  $$ = $1;
+}
+FIELD_VALUE:
+        STRING_VALUE
+        {
+          $$ = malloc(sizeof(value));
+          $$->svalue = $1;
+        }
+        |
+        INT_VALUE
+        {
+          $$ = malloc(sizeof(value));
+          $$->ivalue = $1;
+        }
+
+%%
+void *yy_scan_string(char *, void *);
+void yy_delete_buffer(void *, void *);
+
+void
+close_query (query *q) {
+  free(q->w->column_name);
+  free(q->w->v->svalue);
+  free(q->w->v);
+  free(q->w);
+
+  free(q->f->table);
+  free(q->f);
+}
+
+int
+main(int argc, char **argv) {
+  /* yydebug = 1; */
+  void *scanner;
+  yylex_init(&scanner);
+  query q;
+  void *buffer = yy_scan_string("select from t where foo = '5' ;", scanner);
+  yyparse (&q, scanner);
+  yy_delete_buffer(buffer, scanner);
+  printf("table name: %s\n", q.f->table);
+  printf("where column: %s, value: %s\n", q.w->column_name, q.w->v->svalue);
+  yylex_destroy(scanner);
+  close_query(&q);
+  return 0;
+}
+
+int yyerror(query *q, void *s, char *err) {
+  fprintf(stderr, "error: %s\n", err);
+}

src/query/query_types.h

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+typedef struct {
+  char *table;
+} from;
+
+typedef enum {
+  OP_EQUAL
+} operation_t;
+
+typedef union {
+  int ivalue;
+  char *svalue;
+} value;
+
+typedef struct {
+  char *column_name;
+  operation_t op;
+  value *v;
+} where;
+
+typedef struct {
+  from *f;
+  where *w;
+  char *error;
+} query;

src/query/y.tab.h

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+/* A Bison parser, made by GNU Bison 2.5.  */
+
+/* Bison interface for Yacc-like parsers in C
+   
+      Copyright (C) 1984, 1989-1990, 2000-2011 Free Software Foundation, Inc.
+   
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* As a special exception, you may create a larger work that contains
+   part or all of the Bison parser skeleton and distribute that work
+   under terms of your choice, so long as that work isn't itself a
+   parser generator using the skeleton or a modified version thereof
+   as a parser skeleton.  Alternatively, if you modify or redistribute
+   the parser skeleton itself, you may (at your option) remove this
+   special exception, which will cause the skeleton and the resulting
+   Bison output files to be licensed under the GNU General Public
+   License without this special exception.
+   
+   This special exception was added by the Free Software Foundation in
+   version 2.2 of Bison.  */
+
+
+/* Tokens.  */
+#ifndef YYTOKENTYPE
+# define YYTOKENTYPE
+   /* Put the tokens into the symbol table, so that GDB and other debuggers
+      know about them.  */
+   enum yytokentype {
+     SELECT = 258,
+     FROM = 259,
+     WHERE = 260,
+     EQUAL = 261,
+     NAME = 262,
+     STRING_VALUE = 263,
+     INT_VALUE = 264
+   };
+#endif
+/* Tokens.  */
+#define SELECT 258
+#define FROM 259
+#define WHERE 260
+#define EQUAL 261
+#define NAME 262
+#define STRING_VALUE 263
+#define INT_VALUE 264
+
+
+
+
+#if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
+typedef union YYSTYPE
+{
+
+/* Line 2068 of yacc.c  */
+#line 6 "query.yacc"
+
+  char *string;
+  int i;
+  from *f;
+  where *w;
+  value *v;
+
+
+
+/* Line 2068 of yacc.c  */
+#line 78 "y.tab.h"
+} YYSTYPE;
+# define YYSTYPE_IS_TRIVIAL 1
+# define yystype YYSTYPE /* obsolescent; will be withdrawn */
+# define YYSTYPE_IS_DECLARED 1
+#endif
+
+
+
+