python-readonly-statement-20100502.patch.diff

diff -ur Python-2.6.5~/Grammar/Grammar Python-2.6.5/Grammar/Grammar
--- Python-2.6.5~/Grammar/Grammar	2008-08-20 04:52:46.000000000 +0900
+++ Python-2.6.5/Grammar/Grammar	2010-05-02 17:23:23.000000000 +0900
@@ -45,9 +45,10 @@
 stmt: simple_stmt | compound_stmt
 simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
 small_stmt: (expr_stmt | print_stmt  | del_stmt | pass_stmt | flow_stmt |
-             import_stmt | global_stmt | exec_stmt | assert_stmt)
+             import_stmt | global_stmt | exec_stmt | assert_stmt | const_stmt)
 expr_stmt: testlist (augassign (yield_expr|testlist) |
                      ('=' (yield_expr|testlist))*)
+const_stmt: 'readonly' testlist ('=' (yield_expr|testlist))+
 augassign: ('+=' | '-=' | '*=' | '/=' | '%=' | '&=' | '|=' | '^=' |
             '<<=' | '>>=' | '**=' | '//=')
 # For normal assignments, additional restrictions enforced by the interpreter
diff -ur Python-2.6.5~/Include/symtable.h Python-2.6.5/Include/symtable.h
--- Python-2.6.5~/Include/symtable.h	2008-08-17 10:27:30.000000000 +0900
+++ Python-2.6.5/Include/symtable.h	2010-05-02 16:38:45.000000000 +0900
@@ -72,6 +72,7 @@
 #define DEF_FREE_GLOBAL 2<<7   /* free variable is actually implicit global */
 #define DEF_FREE_CLASS 2<<8    /* free variable from class's method */
 #define DEF_IMPORT 2<<9        /* assignment occurred via import */
+#define DEF_CONST 2<<14        /* name is marked as constant */	
 
 #define DEF_BOUND (DEF_LOCAL | DEF_PARAM | DEF_IMPORT)
 
diff -ur Python-2.6.5~/Modules/getbuildinfo.c Python-2.6.5/Modules/getbuildinfo.c
--- Python-2.6.5~/Modules/getbuildinfo.c	2009-05-24 04:35:33.000000000 +0900
+++ Python-2.6.5/Modules/getbuildinfo.c	2010-05-02 17:41:11.000000000 +0900
@@ -36,7 +36,7 @@
 	const char *sep = *revision ? ":" : "";
 	const char *branch = Py_SubversionShortBranch();
 	PyOS_snprintf(buildinfo, sizeof(buildinfo),
-		      "%s%s%s, %.20s, %.9s", branch, sep, revision, 
+		      "%s%s%s, 魔改造, %.20s, %.9s", branch, sep, revision, 
 		      DATE, TIME);
 	return buildinfo;
 }
diff -ur Python-2.6.5~/Parser/Python.asdl Python-2.6.5/Parser/Python.asdl
--- Python-2.6.5~/Parser/Python.asdl	2008-03-30 15:40:17.000000000 +0900
+++ Python-2.6.5/Parser/Python.asdl	2010-05-02 15:53:17.000000000 +0900
@@ -80,7 +80,7 @@
 	      -- col_offset is the byte offset in the utf8 string the parser uses
 	      attributes (int lineno, int col_offset)
 
-	expr_context = Load | Store | Del | AugLoad | AugStore | Param
+	expr_context = Load | Store | Del | AugLoad | AugStore | Param | ConstStore
 
 	slice = Ellipsis | Slice(expr? lower, expr? upper, expr? step) 
 	      | ExtSlice(slice* dims) 
diff -ur Python-2.6.5~/Python/ast.c Python-2.6.5/Python/ast.c
--- Python-2.6.5~/Python/ast.c	2009-11-20 08:01:36.000000000 +0900
+++ Python-2.6.5/Python/ast.c	2010-05-02 16:06:21.000000000 +0900
@@ -2181,6 +2181,52 @@
 }
 
 static stmt_ty
+ast_for_const_stmt(struct compiling *c, const node *n)
+{
+    int i;
+    asdl_seq *targets;
+    node *value;
+    expr_ty expression;
+
+    REQ(n, const_stmt);
+    /* const_stmt: 'const' testlist ('=' (yield_expr|testlist))+ */
+
+    /* a normal assignment */
+    REQ(CHILD(n, 0), NAME);
+    REQ(CHILD(n, 2), EQUAL);
+    targets = asdl_seq_new((NCH(n) - 2) / 2, c->c_arena);
+    if (!targets)
+        return NULL;
+    for (i = 1; i < NCH(n) - 2; i += 2) {
+        expr_ty e;
+        node *ch = CHILD(n, i);
+        if (TYPE(ch) == yield_expr) {
+            ast_error(ch, "assignment to yield expression not possible");
+            return NULL;
+        }
+        e = ast_for_testlist(c, ch);
+
+        /* set context to assign */
+        if (!e) 
+            return NULL;
+
+        if (!set_context(c, e, ConstStore, ch))
+            return NULL;
+
+        asdl_seq_SET(targets, i / 2, e);
+    }
+    value = CHILD(n, NCH(n) - 1);
+    if (TYPE(value) == testlist)
+        expression = ast_for_testlist(c, value);
+    else
+        expression = ast_for_expr(c, value);
+    if (!expression)
+        return NULL;
+    return Assign(targets, expression, LINENO(n), n->n_col_offset,
+                  c->c_arena);
+}
+
+static stmt_ty
 ast_for_print_stmt(struct compiling *c, const node *n)
 {
     /* print_stmt: 'print' ( [ test (',' test)* [','] ]
@@ -3121,11 +3167,13 @@
         n = CHILD(n, 0);
         /* small_stmt: expr_stmt | print_stmt  | del_stmt | pass_stmt
                      | flow_stmt | import_stmt | global_stmt | exec_stmt
-                     | assert_stmt
+                     | assert_stmt | const_stmt
         */
         switch (TYPE(n)) {
             case expr_stmt:
                 return ast_for_expr_stmt(c, n);
+            case const_stmt:
+                return ast_for_const_stmt(c, n);
             case print_stmt:
                 return ast_for_print_stmt(c, n);
             case del_stmt:
diff -ur Python-2.6.5~/Python/compile.c Python-2.6.5/Python/compile.c
--- Python-2.6.5~/Python/compile.c	2009-11-29 01:37:36.000000000 +0900
+++ Python-2.6.5/Python/compile.c	2010-05-02 16:05:38.000000000 +0900
@@ -2337,7 +2337,7 @@
 	/* XXX AugStore isn't used anywhere! */
 
 	/* First check for assignment to __debug__. Param? */
-	if ((ctx == Store || ctx == AugStore || ctx == Del)
+	if ((ctx == Store || ctx == ConstStore || ctx == AugStore || ctx == Del)
 	    && !strcmp(PyString_AS_STRING(name), "__debug__")) {
 		return compiler_error(c, "can not assign to __debug__");
 	}
@@ -2382,7 +2382,7 @@
 	case OP_DEREF:
 		switch (ctx) {
 		case Load: op = LOAD_DEREF; break;
-		case Store: op = STORE_DEREF; break;
+		case Store: case ConstStore: op = STORE_DEREF; break;
 		case AugLoad:
 		case AugStore:
 			break;
@@ -2403,7 +2403,7 @@
 	case OP_FAST:
 		switch (ctx) {
 		case Load: op = LOAD_FAST; break;
-		case Store: op = STORE_FAST; break;
+		case Store: case ConstStore: op = STORE_FAST; break;
 		case Del: op = DELETE_FAST; break;
 		case AugLoad:
 		case AugStore:
@@ -2420,7 +2420,7 @@
 	case OP_GLOBAL:
 		switch (ctx) {
 		case Load: op = LOAD_GLOBAL; break;
-		case Store: op = STORE_GLOBAL; break;
+		case Store: case ConstStore: op = STORE_GLOBAL; break;
 		case Del: op = DELETE_GLOBAL; break;
 		case AugLoad:
 		case AugStore:
@@ -2435,7 +2435,7 @@
 	case OP_NAME:
 		switch (ctx) {
 		case Load: op = LOAD_NAME; break;
-		case Store: op = STORE_NAME; break;
+		case Store: case ConstStore: op = STORE_NAME; break;
 		case Del: op = DELETE_NAME; break;
 		case AugLoad:
 		case AugStore:
@@ -3040,7 +3040,7 @@
 		case AugStore:
 			ADDOP(c, ROT_TWO);
 			/* Fall through to save */
-		case Store:
+		case Store: case ConstStore:
 			ADDOP_NAME(c, STORE_ATTR, e->v.Attribute.attr, names);
 			break;
 		case Del:
@@ -3066,7 +3066,7 @@
 		case AugStore:
 			VISIT_SLICE(c, e->v.Subscript.slice, AugStore);
 			break;
-		case Store:
+		case Store: case ConstStore:
 			VISIT(c, expr, e->v.Subscript.value);
 			VISIT_SLICE(c, e->v.Subscript.slice, Store);
 			break;
@@ -3214,7 +3214,7 @@
 		case AugLoad: /* fall through to Load */
 		case Load:    op = BINARY_SUBSCR; break;
 		case AugStore:/* fall through to Store */
-		case Store:   op = STORE_SUBSCR; break;
+		case ConstStore: case Store:   op = STORE_SUBSCR; break;
 		case Del:     op = DELETE_SUBSCR; break;
 		case Param:
 			PyErr_Format(PyExc_SystemError, 
@@ -3299,7 +3299,7 @@
 	case AugLoad: /* fall through to Load */
 	case Load: op = SLICE; break;
 	case AugStore:/* fall through to Store */
-	case Store: op = STORE_SLICE; break;
+	case Store: case ConstStore: op = STORE_SLICE; break;
 	case Del: op = DELETE_SLICE; break;
 	case Param:
 	default:
diff -ur Python-2.6.5~/Python/symtable.c Python-2.6.5/Python/symtable.c
--- Python-2.6.5~/Python/symtable.c	2009-11-20 10:19:48.000000000 +0900
+++ Python-2.6.5/Python/symtable.c	2010-05-02 17:35:20.000000000 +0900
@@ -11,6 +11,18 @@
 #define GLOBAL_AFTER_USE \
 "name '%.400s' is used prior to global declaration"
 
+#define CONST_AFTER_ASSIGN \
+"name '%.400s' is assigned to before readonly declaration"
+
+#define CONST_AFTER_PARAM \
+"name '%.400s' already appeared in function parameters"
+
+#define CONST_AFTER_USE \
+"name '%.400s' is used prior to readonly declaration"
+
+#define CONST_VARIABLE \
+"variable '%.400s' is read-only"
+
 #define IMPORT_STAR_WARNING "import * only allowed at module level"
 
 #define RETURN_VAL_IN_GENERATOR \
@@ -390,6 +402,15 @@
 		}
 		return 1;
 	}
+	if (flags & DEF_CONST) {
+		if (flags & DEF_PARAM) {
+			PyErr_Format(PyExc_SyntaxError, CONST_AFTER_PARAM,
+			             PyString_AS_STRING(name));
+			PyErr_SyntaxLocation(ste->ste_table->st_filename,
+					     ste->ste_lineno);
+			return 0;
+		}
+	}
 	if (flags & DEF_BOUND) {
 		SET_SCOPE(dict, name, LOCAL);
 		if (PyDict_SetItem(local, name, Py_None) < 0)
@@ -1285,11 +1306,52 @@
 		VISIT(st, expr, e->v.Subscript.value);
 		VISIT(st, slice, e->v.Subscript.slice);
 		break;
-        case Name_kind:
-		if (!symtable_add_def(st, e->v.Name.id, 
-				      e->v.Name.ctx == Load ? USE : DEF_LOCAL))
-			return 0;
+        case Name_kind: {
+		if (e->v.Name.ctx != Load) {
+			long cur = symtable_lookup(st, e->v.Name.id);
+			if (cur < 0)
+				return 0;
+			if (e->v.Name.ctx == ConstStore && cur & (DEF_LOCAL | USE)) {
+				char *c_name = PyString_AS_STRING(e->v.Name.id);
+				if (cur & DEF_LOCAL) 
+					PyErr_Format(PyExc_SyntaxError,
+						     CONST_AFTER_ASSIGN,
+						     c_name);
+				else
+					PyErr_Format(PyExc_SyntaxError,
+						     CONST_AFTER_USE,
+						     c_name);
+				PyErr_SyntaxLocation(st->st_filename,
+						     e->lineno);
+				return 0;
+			}
+			else if ((cur & DEF_CONST)) {
+				PyErr_Format(PyExc_SyntaxError,
+					     CONST_VARIABLE,
+					     PyString_AS_STRING(e->v.Name.id));
+				PyErr_SyntaxLocation(st->st_filename,
+						     e->lineno);
+				return 0;
+			}
+		}
+		{
+			long flag = 0;
+			switch (e->v.Name.ctx) {
+			case Load:
+				flag = USE;
+				break;
+			case Store:
+				flag = DEF_LOCAL;
+				break;
+			case ConstStore:
+				flag = DEF_LOCAL | DEF_CONST;
+				break;
+			}
+			if (!symtable_add_def(st, e->v.Name.id, flag))
+				return 0;
+		}
 		break;
+	}
 	/* child nodes of List and Tuple will have expr_context set */
         case List_kind:
 		VISIT_SEQ(st, expr, e->v.List.elts);