added documentation to lexer and grammar files

src/bison/bison_parser.y

@@ -1,23 +1,43 @@
 %{
-
+/**
-/*
+ * bison_parser.y
- * parser.y file
+ * defines bison_parser.h
- * To generate the parser run: "bison parser.y"
+ * outputs bison_parser.c
+ * 
+ * Grammar File Spec: http://dinosaur.compilertools.net/bison/bison_6.html
+ *
  */
+/*********************************
+ ** Section 1: C Declarations
+ *********************************/
 
 #include "Statement.h"
 #include "List.h"
 #include "bison_parser.h"
 #include "flex_lexer.h"
 
-#include <iostream>
+#include <stdio.h>
 
 int yyerror(Statement **expression, yyscan_t scanner, const char *msg) {
-    // Add error handling routine as needed
+	fprintf(stderr, "[Error] SQL Parser: %s\n", msg);
+	return 0;
 }
 
 %}
+/*********************************
+ ** Section 2: Bison Parser Declarations
+ *********************************/
 
+
+// Define the names of the created files
+%output  "bison_parser.c"
+%defines "bison_parser.h"
+
+// Tell bison to create a reentrant parser
+%define api.pure full
+
+
+// Specify code that is included in the generated .h and .c files
 %code requires {
 
 #ifndef YYtypeDEF_YY_SCANNER_T
@@ -27,14 +47,18 @@ typedef void* yyscan_t;
 
 }
 
-%output  "bison_parser.c"
+// Define additional parameters for yylex (http://www.gnu.org/software/bison/manual/html_node/Pure-Calling.html)
-%defines "bison_parser.h"
-
-%define api.pure
 %lex-param   { yyscan_t scanner }
+
+// Define additional parameters for yyparse
 %parse-param { Statement **statement }
 %parse-param { yyscan_t scanner }
 
+
+
+/*********************************
+ ** Define all data-types (http://www.gnu.org/software/bison/manual/html_node/Union-Decl.html)
+ *********************************/
 %union {
 	float number;
 	char* sval;
@@ -48,39 +72,58 @@ typedef void* yyscan_t;
 	List<Expr*>* explist;
 }
 
-%token SELECT FROM GROUP BY WHERE NOT AND OR
 
+
+/*********************************
+ ** Token Definition
+ *********************************/
+%token SELECT FROM GROUP BY WHERE NOT AND OR
 %token <sval> NAME STRING COMPARISON
 %token <number> INTNUM
 
+
+
+/*********************************
+ ** Non-Terminal types (http://www.gnu.org/software/bison/manual/html_node/Type-Decl.html)
+ *********************************/
 %type <statement> statement
 %type <select_statement> select_statement
 %type <sval> table_name
 %type <table> from_clause table_exp
-
 %type <expr> expr column_name scalar_exp literal
 %type <expr> comparison_predicate predicate search_condition where_clause
-
 %type <slist> table_ref_commalist
 %type <explist> expr_list group_clause
+
+
+
 %%
+/*********************************
+ ** Section 3: Grammar Definition
+ *********************************/
 
 
+// Defines our general input.
+// TODO: Support list of statements
 input:
 		statement opt_semicolon { *statement = $1; }
 	;
 
+// All types of statements
+// Atm: only select statements (future: insert, delete, etc...)
 statement:
 		select_statement { $$ = $1; }
 	|	/* empty */ { $$ = NULL; }
 	;
 
 
-////// TODO:
+/******************************
-// join
+ ** Select Statements
-// limit
+ ******************************/
-// order by
 
+// TODO: join
+// TODO: limit
+// TODO: order by
 select_statement:
 		SELECT expr_list from_clause where_clause group_clause
 		{
@@ -99,18 +142,20 @@ from_clause:
 		FROM table_exp { $$ = $2; }
 	;
 
+
 where_clause:
 		WHERE search_condition { $$ = $2; }
 	|	/* empty */ { $$ = NULL; }
 	;
 
+// TODO: having
 group_clause:
 		GROUP BY expr_list { $$ = $3; }
 	|	/* empty */ { $$ = NULL; }
 	;
 
 
-
+// TODO: comma_list with mixed table names and select statements
 table_exp:
 		table_ref_commalist {
 			TableRef* t = new TableRef(eTableName);
@@ -125,41 +170,34 @@ table_exp:
 	;
 
 
+// TODO: multiple predicates
 search_condition:
 		predicate
 	;
 
+
 predicate:
 		comparison_predicate
 	;
 
+
 comparison_predicate:
 		scalar_exp COMPARISON scalar_exp { $$ = makePredicate($1, $2, $3); }
 	;
 
-
+// TODO: Expression can also be scalar_exp
 expr:
 		column_name
 	|	NAME '(' expr ')' { $$ = makeFunctionRef($1, $3); }
 	;
 
 
-
+// TODO: Scalar expressions can also be arithmetic
-/* Lists */
+scalar_exp:
-expr_list:
+		column_name
-		expr { $$ = new List<Expr*>($1); }
+	|	literal
-	|	expr_list ',' expr { $1->push_back($3); $$ = $1; }
 	;
 
-
-// TODO: add table_ref to include names and select queries
-table_ref_commalist:
-		table_name { $$ = new List<char*>($1); }
-	|	table_ref_commalist ',' table_name { $1->push_back($3); $$ = $1; }
-	;
-/* / Lists */
-
-
 column_name:
 		NAME { $$ = makeColumnRef($1); }
 	;
@@ -174,13 +212,33 @@ literal:
 	|	INTNUM { $$ = makeFloatLiteral($1); }
 	;
 
-scalar_exp:
-		column_name
-	|	literal
-	;
 
 opt_semicolon:
 		';'
 	|	/* empty */
 	;
+
+
+/******************************
+ ** Lists 
+ ******************************/
+expr_list:
+		expr { $$ = new List<Expr*>($1); }
+	|	expr_list ',' expr { $1->push_back($3); $$ = $1; }
+	;
+
+// TODO: add table_ref to include names and select queries
+table_ref_commalist:
+		table_name { $$ = new List<char*>($1); }
+	|	table_ref_commalist ',' table_name { $1->push_back($3); $$ = $1; }
+	;
+
+
+
 %%
+/*********************************
+ ** Section 4: Additional C code
+ *********************************/
+
+/* empty */
+

src/bison/flex_lexer.l

@@ -1,32 +1,50 @@
-%{
+/**
-
+ * lexer
-/*
+ *
- * lexer.l file
+ *
- * To generate the lexical analyzer run: "flex lexer.l"
  */
 
+
+/***************************
+ ** Section 1: Definitions
+ ***************************/
+%{
+
 #include "Statement.h"
 #include "List.h"
 #include "bison_parser.h"
-
 #include <stdio.h>
-#include <iostream>
-using namespace std;
 
 #define TOK(name) { return name; }
 
 %}
+/***************************
+ ** Section 2: Rules
+ ***************************/
 
+/* Define the output files */
+%option header-file="flex_lexer.h"
+%option outfile="flex_lexer.c"
 
-%option outfile="flex_lexer.c" header-file="flex_lexer.h"
+/* Make reentrant */
-%option warn nodefault
+%option reentrant bison-bridge
-%option reentrant noyywrap never-interactive nounistd
+
-%option bison-bridge
+/* performance tweeks */
+%option never-interactive batch
+
+/* other flags */
+%option noyywrap warn
 %option case-insensitive
+/* %option nodefault */
 
+
+
+/***************************
+ ** Section 3: Rules
+ ***************************/
 %%
 
-[ \t\n]+	;
+[ \t\n]+	/* skip whitespace */;
 
 SELECT	TOK(SELECT)
 FROM	TOK(FROM)
@@ -69,8 +87,14 @@ OR		TOK(OR)
 	return STRING;
 }
 
+
+
+
 %%
+/***************************
+ ** Section 3: User code
+ ***************************/
 
 int yyerror(const char *msg) {
-    fprintf(stderr,"Error:%s\n",msg); return 0;
+    fprintf(stderr, "[Error] SQL Lexer: %s\n",msg); return 0;
 }