From 8d34d3305544826972af57d2cf5246326201643d Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Thu, 20 Dec 2012 10:02:00 +0900
Subject: [PATCH] Implement "if not (foo)" syntax.

It is syntactic sugar for if (!(foo)), but is useful for avoiding
inconsistencies between such things as if (string) and if (!string), even
though qcc can't parse if not (string). It also makes for easier to read
code when the logic in the condition is complex.
---
 tools/qfcc/include/expr.h    |  3 ++-
 tools/qfcc/source/expr.c     | 11 ++++++++---
 tools/qfcc/source/qc-lex.l   |  1 +
 tools/qfcc/source/qc-parse.y | 17 +++++++++++------
 tools/qfcc/source/qp-parse.y |  4 ++--
 5 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/tools/qfcc/include/expr.h b/tools/qfcc/include/expr.h
index 713292fbf..a3348e9d7 100644
--- a/tools/qfcc/include/expr.h
+++ b/tools/qfcc/include/expr.h
@@ -598,7 +598,8 @@ expr_t *incop_expr (int op, expr_t *e, int postop);
 expr_t *array_expr (expr_t *array, expr_t *index);
 expr_t *pointer_expr (expr_t *pointer);
 expr_t *address_expr (expr_t *e1, expr_t *e2, struct type_s *t);
-expr_t *build_if_statement (expr_t *test, expr_t *s1, expr_t *els, expr_t *s2);
+expr_t *build_if_statement (int not, expr_t *test, expr_t *s1, expr_t *els,
+							expr_t *s2);
 expr_t *build_while_statement (expr_t *test, expr_t *statement,
 							   expr_t *break_label, expr_t *continue_label);
 expr_t *build_do_while_statement (expr_t *statement, expr_t *test,
diff --git a/tools/qfcc/source/expr.c b/tools/qfcc/source/expr.c
index 8f72240cf..109d0a51f 100644
--- a/tools/qfcc/source/expr.c
+++ b/tools/qfcc/source/expr.c
@@ -2284,7 +2284,7 @@ address_expr (expr_t *e1, expr_t *e2, type_t *t)
 }
 
 expr_t *
-build_if_statement (expr_t *test, expr_t *s1, expr_t *els, expr_t *s2)
+build_if_statement (int not, expr_t *test, expr_t *s1, expr_t *els, expr_t *s2)
 {
 	int         line = pr.source_line;
 	string_t    file = pr.source_file;
@@ -2299,8 +2299,13 @@ build_if_statement (expr_t *test, expr_t *s1, expr_t *els, expr_t *s2)
 
 	test = convert_bool (test, 1);
 	if (test->type != ex_error) {
-		backpatch (test->e.bool.true_list, tl);
-		backpatch (test->e.bool.false_list, fl);
+		if (not) {
+			backpatch (test->e.bool.true_list, fl);
+			backpatch (test->e.bool.false_list, tl);
+		} else {
+			backpatch (test->e.bool.true_list, tl);
+			backpatch (test->e.bool.false_list, fl);
+		}
 		append_expr (test->e.bool.e, tl);
 		append_expr (if_expr, test);
 	}
diff --git a/tools/qfcc/source/qc-lex.l b/tools/qfcc/source/qc-lex.l
index ff0f89e8a..7d190cb48 100644
--- a/tools/qfcc/source/qc-lex.l
+++ b/tools/qfcc/source/qc-lex.l
@@ -319,6 +319,7 @@ static keyword_t at_keywords[] = {
 	{"static",		STATIC	},
 	{"sizeof",		SIZEOF	},
 	{"nosave",		NOSAVE	},
+	{"not",			NOT		},
 };
 
 // These keywords require the QuakeForge VM to be of any use. ie, they cannot
diff --git a/tools/qfcc/source/qc-parse.y b/tools/qfcc/source/qc-parse.y
index ef7bd1cf6..7304f7f0e 100644
--- a/tools/qfcc/source/qc-parse.y
+++ b/tools/qfcc/source/qc-parse.y
@@ -145,7 +145,7 @@ int yylex (void);
 
 %token				LOCAL RETURN WHILE DO IF ELSE FOR BREAK CONTINUE ELLIPSIS
 %token				NIL IFBE IFB IFAE IFA SWITCH CASE DEFAULT ENUM TYPEDEF
-%token				ARGS EXTERN STATIC SYSTEM NOSAVE OVERLOAD
+%token				ARGS EXTERN STATIC SYSTEM NOSAVE OVERLOAD NOT
 %token	<op>		STRUCT
 %token	<type>		TYPE
 %token	<symbol>	OBJECT TYPE_NAME
@@ -205,7 +205,7 @@ int yylex (void);
 %type	<protocol>	protocol_name
 %type	<methodlist> methodprotolist methodprotolist2
 %type	<symtab>	ivar_decl_list
-%type	<op>		ci
+%type	<op>		ci not
 
 %{
 
@@ -1149,13 +1149,13 @@ statement
 			switch_block = $5;
 			break_label = $2;
 		}
-	| IF '(' texpr ')' statement %prec IFX
+	| IF not '(' texpr ')' statement %prec IFX
 		{
-			$$ = build_if_statement ($3, $5, 0, 0);
+			$$ = build_if_statement ($2, $4, $6, 0, 0);
 		}
-	| IF '(' texpr ')' statement else statement
+	| IF not '(' texpr ')' statement else statement
 		{
-			$$ = build_if_statement ($3, $5, $6, $7);
+			$$ = build_if_statement ($2, $4, $6, $7, $8);
 		}
 	| FOR break_label continue_label
 			'(' opt_expr ';' opt_expr ';' opt_expr ')' statement
@@ -1184,6 +1184,11 @@ statement
 		}
 	;
 
+not
+	: NOT						{ $$ = 1; }
+	| /* empty */				{ $$ = 0; }
+	;
+
 else
 	: ELSE
 		{
diff --git a/tools/qfcc/source/qp-parse.y b/tools/qfcc/source/qp-parse.y
index f8c870ed4..a2b94acea 100644
--- a/tools/qfcc/source/qp-parse.y
+++ b/tools/qfcc/source/qp-parse.y
@@ -354,11 +354,11 @@ statement
 	| compound_statement
 	| IF expression THEN statement else statement
 		{
-			$$ = build_if_statement ($2, $4, $5, $6);
+			$$ = build_if_statement (0, $2, $4, $5, $6);
 		}
 	| IF expression THEN statement %prec IFX
 		{
-			$$ = build_if_statement ($2, $4, 0, 0);
+			$$ = build_if_statement (0, $2, $4, 0, 0);
 		}
 	| WHILE expression DO statement
 		{