from __future__ import with_statement addon for 'with', mostly written by

Neal.

3 files changed, 65 insertions, 31 deletions

diff --git a/Parser/parser.c b/Parser/parser.c
index 686161b..cad5ce2 100644
--- a/Parser/parser.c
+++ b/Parser/parser.c
@@ -79,8 +79,8 @@ PyParser_New(grammar *g, int start)
 	if (ps == NULL)
 		return NULL;
 	ps->p_grammar = g;
-#if 0 /* future keyword */
-	ps->p_generators = 0;
+#ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
+	ps->p_flags = 0;
 #endif
 	ps->p_tree = PyNode_New(start);
 	if (ps->p_tree == NULL) {
@@ -147,10 +147,10 @@ classify(parser_state *ps, int type, char *str)
 			if (l->lb_type == NAME && l->lb_str != NULL &&
 					l->lb_str[0] == s[0] &&
 					strcmp(l->lb_str, s) == 0) {
-#if 0 /* future keyword */
-				if (!ps->p_generators &&
-				    s[0] == 'y' &&
-				    strcmp(s, "yield") == 0)
+#ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
+				if (!(ps->p_flags & CO_FUTURE_WITH_STATEMENT) &&
+				    s[0] == 'w' &&
+				    strcmp(s, "with") == 0)
 					break; /* not a keyword */
 #endif
 				D(printf("It's a keyword\n"));
@@ -174,7 +174,7 @@ classify(parser_state *ps, int type, char *str)
 	return -1;
 }
 
-#if 0 /* future keyword */
+#ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
 static void
 future_hack(parser_state *ps)
 {
@@ -182,16 +182,27 @@ future_hack(parser_state *ps)
 	node *ch;
 	int i;
 
-	if (strcmp(STR(CHILD(n, 0)), "from") != 0)
+	/* from __future__ import ..., must have at least 4 children */
+	n = CHILD(n, 0);
+	if (NCH(n) < 4)
+		return;
+	ch = CHILD(n, 0);
+	if (STR(ch) == NULL || strcmp(STR(ch), "from") != 0)
 		return;
 	ch = CHILD(n, 1);
-	if (strcmp(STR(CHILD(ch, 0)), "__future__") != 0)
+	if (NCH(ch) == 1 && STR(CHILD(ch, 0)) &&
+	    strcmp(STR(CHILD(ch, 0)), "__future__") != 0)
 		return;
 	for (i = 3; i < NCH(n); i += 2) {
+		/* XXX: assume we don't have parentheses in import:
+		        from __future__ import (x, y, z)
+		*/
 		ch = CHILD(n, i);
+		if (NCH(ch) == 1)
+			ch = CHILD(ch, 0);
 		if (NCH(ch) >= 1 && TYPE(CHILD(ch, 0)) == NAME &&
-		    strcmp(STR(CHILD(ch, 0)), "generators") == 0) {
-			ps->p_generators = 1;
+		    strcmp(STR(CHILD(ch, 0)), "with_statement") == 0) {
+			ps->p_flags |= CO_FUTURE_WITH_STATEMENT;
 			break;
 		}
 	}
@@ -255,7 +266,7 @@ PyParser_AddToken(register parser_state *ps, register int type, char *str,
 						 "Direct pop.\n",
 						 d->d_name,
 						 ps->p_stack.s_top->s_state));
-#if 0 /* future keyword */
+#ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
 					if (d->d_name[0] == 'i' &&
 					    strcmp(d->d_name,
 						   "import_stmt") == 0)
@@ -273,7 +284,7 @@ PyParser_AddToken(register parser_state *ps, register int type, char *str,
 		}
 		
 		if (s->s_accept) {
-#if 0 /* future keyword */
+#ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
 			if (d->d_name[0] == 'i' &&
 			    strcmp(d->d_name, "import_stmt") == 0)
 				future_hack(ps);
diff --git a/Parser/parser.h b/Parser/parser.h
index 95ec247..f5d2d0d 100644
--- a/Parser/parser.h
+++ b/Parser/parser.h
@@ -25,8 +25,8 @@ typedef struct {
 	stack	 	p_stack;	/* Stack of parser states */
 	grammar		*p_grammar;	/* Grammar to use */
 	node		*p_tree;	/* Top of parse tree */
-#if 0 /* future keyword */
-	int		p_generators;	/* 1 if yield is a keyword */
+#ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
+	unsigned long	p_flags;	/* see co_flags in Include/code.h */
 #endif
 } parser_state;
 
diff --git a/Parser/parsetok.c b/Parser/parsetok.c
index 4c533f1..cf445e1 100644
--- a/Parser/parsetok.c
+++ b/Parser/parsetok.c
@@ -92,10 +92,19 @@ PyParser_ParseFileFlags(FILE *fp, const char *filename, grammar *g, int start,
 /* Parse input coming from the given tokenizer structure.
    Return error code. */
 
-#if 0 /* future keyword */
-static char yield_msg[] =
-"%s:%d: Warning: 'yield' will become a reserved keyword in the future\n";
-#endif
+static char with_msg[] =
+"%s:%d: Warning: 'with' will become a reserved keyword in Python 2.6\n";
+
+static char as_msg[] =
+"%s:%d: Warning: 'as' will become a reserved keyword in Python 2.6\n";
+
+static void
+warn(const char *msg, const char *filename, int lineno)
+{
+	if (filename == NULL)
+		filename = "<string>";
+	PySys_WriteStderr(msg, filename, lineno);
+}
 
 static node *
 parsetok(struct tok_state *tok, grammar *g, int start, perrdetail *err_ret,
@@ -103,7 +112,7 @@ parsetok(struct tok_state *tok, grammar *g, int start, perrdetail *err_ret,
 {
 	parser_state *ps;
 	node *n;
-	int started = 0;
+	int started = 0, handling_import = 0, handling_with = 0;
 
 	if ((ps = PyParser_New(g, start)) == NULL) {
 		fprintf(stderr, "no mem for new parser\n");
@@ -111,9 +120,9 @@ parsetok(struct tok_state *tok, grammar *g, int start, perrdetail *err_ret,
 		PyTokenizer_Free(tok);
 		return NULL;
 	}
-#if 0 /* future keyword */
-	if (flags & PyPARSE_YIELD_IS_KEYWORD)
-		ps->p_generators = 1;
+#ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
+	if (flags & PyPARSE_WITH_IS_KEYWORD)
+		ps->p_flags |= CO_FUTURE_WITH_STATEMENT;
 #endif
 
 	for (;;) {
@@ -129,6 +138,7 @@ parsetok(struct tok_state *tok, grammar *g, int start, perrdetail *err_ret,
 		}
 		if (type == ENDMARKER && started) {
 			type = NEWLINE; /* Add an extra newline */
+			handling_with = handling_import = 0;
 			started = 0;
 			/* Add the right number of dedent tokens,
 			   except if a certain flag is given --
@@ -153,14 +163,27 @@ parsetok(struct tok_state *tok, grammar *g, int start, perrdetail *err_ret,
 			strncpy(str, a, len);
 		str[len] = '\0';
 
-#if 0 /* future keyword */
-		/* Warn about yield as NAME */
-		if (type == NAME && !ps->p_generators &&
-		    len == 5 && str[0] == 'y' && strcmp(str, "yield") == 0)
-			PySys_WriteStderr(yield_msg,
-					  err_ret->filename==NULL ?
-					  "<string>" : err_ret->filename,
-					  tok->lineno);
+#ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
+		/* This is only necessary to support the "as" warning, but
+		   we don't want to warn about "as" in import statements. */
+		if (type == NAME &&
+		    len == 6 && str[0] == 'i' && strcmp(str, "import") == 0)
+			handling_import = 1;
+
+		/* Warn about with as NAME */
+		if (type == NAME &&
+		    !(ps->p_flags & CO_FUTURE_WITH_STATEMENT)) {
+		    if (len == 4 && str[0] == 'w' && strcmp(str, "with") == 0)
+			warn(with_msg, err_ret->filename, tok->lineno);
+		    else if (!(handling_import || handling_with) &&
+			     len == 2 &&
+			     str[0] == 'a' && strcmp(str, "as") == 0)
+			warn(as_msg, err_ret->filename, tok->lineno);
+		}
+		else if (type == NAME &&
+			 (ps->p_flags & CO_FUTURE_WITH_STATEMENT) &&
+			 len == 4 && str[0] == 'w' && strcmp(str, "with") == 0)
+			handling_with = 1;
 #endif
 
 		if ((err_ret->error =