From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Sun, 24 Mar 2019 09:31:56 +0000 (+0000)
Subject: Fictive tags for right alt/cat must be added after adding all tags for left alt/cat.
X-Git-Tag: 1.2~94
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c1fcecefa490c4040532c55a6f09e49549f7b900;p=re2c

Fictive tags for right alt/cat must be added after adding all tags for left alt/cat.

Previous order was incorrect: fictive tags for both left and right
alternative or catenation were added before recursing into the right
alternative or catenation. This resulted in right fictive tags habving
higher precedence than left non-fictive tags.
---

diff --git a/src/regexp/ast_to_re.cc b/src/regexp/ast_to_re.cc
index b969a127..113eae5a 100644
--- a/src/regexp/ast_to_re.cc
+++ b/src/regexp/ast_to_re.cc
@@ -41,9 +41,8 @@ namespace re2c {
  * therefore we have to insert missing captures in subexpressions
  * that influence disambiguation of existing captures. Such cases are:
  * left alternative in union (unless it is already a capture) and first
- * operand in concatenation (unless it is a capture or the length of
- * strings accepted by it is fixed). Of course, this insertion only
- * applies to subexpressions that have nested captures.
+ * operand in concatenation (unless it is a capture). Of course, this
+ * insertion only applies to subexpressions that have nested captures.
  */
 
 static bool has_tags(const AST *);
@@ -128,49 +127,55 @@ RE *ast_to_re(RESpec &spec, const AST *ast, size_t &ncap, int32_t height)
             return re_class(spec, ast->loc, r);
         }
         case AST::ALT: {
+            // see note [POSIX subexpression hierarchy]
+            const bool need_tags = opts->posix_semantics && has_tags(ast);
+
             RE *t1 = NULL, *t2 = NULL, *t3 = NULL, *t4 = NULL, *x, *y;
-            if (opts->posix_semantics && has_tags(ast)) {
-                // see note [POSIX subexpression hierarchy]
-                if (ast->cat.ast1->type != AST::CAP) {
-                    t1 = re_tag(spec, tags.size(), false);
-                    tags.push_back(Tag(Tag::FICTIVE, false, height + 1));
-                    t2 = re_tag(spec, tags.size(), false);
-                    tags.push_back(Tag(Tag::FICTIVE, false, height));
-                }
-                if (ast->cat.ast2->type != AST::CAP) {
-                    t3 = re_tag(spec, tags.size(), false);
-                    tags.push_back(Tag(Tag::FICTIVE, false, height + 1));
-                    t4 = re_tag(spec, tags.size(), false);
-                    tags.push_back(Tag(Tag::FICTIVE, false, height));
-                }
+
+            if (need_tags && ast->alt.ast1->type != AST::CAP) {
+                t1 = re_tag(spec, tags.size(), false);
+                tags.push_back(Tag(Tag::FICTIVE, false, height + 1));
+                t2 = re_tag(spec, tags.size(), false);
+                tags.push_back(Tag(Tag::FICTIVE, false, height));
             }
             x = ast_to_re(spec, ast->alt.ast1, ncap, height);
             x = re_cat(spec, t1, re_cat(spec, x, t2));
+
+            if (need_tags && ast->alt.ast2->type != AST::CAP) {
+                t3 = re_tag(spec, tags.size(), false);
+                tags.push_back(Tag(Tag::FICTIVE, false, height + 1));
+                t4 = re_tag(spec, tags.size(), false);
+                tags.push_back(Tag(Tag::FICTIVE, false, height));
+            }
             y = ast_to_re(spec, ast->alt.ast2, ncap, height);
             y = re_cat(spec, t3, re_cat(spec, y, t4));
+
             return re_alt(spec, x, y);
         }
         case AST::CAT: {
+            // see note [POSIX subexpression hierarchy]
+            const bool need_tags = opts->posix_semantics && has_tags(ast);
+
             RE *t1 = NULL, *t2 = NULL, *t3 = NULL, *t4 = NULL, *x, *y;
-            if (opts->posix_semantics && has_tags(ast)) {
-                // see note [POSIX subexpression hierarchy]
-                if (ast->cat.ast1->type != AST::CAP) {
-                    t1 = re_tag(spec, tags.size(), false);
-                    tags.push_back(Tag(Tag::FICTIVE, false, height + 1));
-                    t2 = re_tag(spec, tags.size(), false);
-                    tags.push_back(Tag(Tag::FICTIVE, false, height));
-                }
-                if (ast->cat.ast2->type != AST::CAP) {
-                    t3 = re_tag(spec, tags.size(), false);
-                    tags.push_back(Tag(Tag::FICTIVE, false, height + 1));
-                    t4 = re_tag(spec, tags.size(), false);
-                    tags.push_back(Tag(Tag::FICTIVE, false, height));
-                }
+
+            if (need_tags && ast->cat.ast1->type != AST::CAP) {
+                t1 = re_tag(spec, tags.size(), false);
+                tags.push_back(Tag(Tag::FICTIVE, false, height + 1));
+                t2 = re_tag(spec, tags.size(), false);
+                tags.push_back(Tag(Tag::FICTIVE, false, height));
             }
             x = ast_to_re(spec, ast->cat.ast1, ncap, height);
             x = re_cat(spec, t1, re_cat(spec, x, t2));
+
+            if (need_tags && ast->cat.ast2->type != AST::CAP) {
+                t3 = re_tag(spec, tags.size(), false);
+                tags.push_back(Tag(Tag::FICTIVE, false, height + 1));
+                t4 = re_tag(spec, tags.size(), false);
+                tags.push_back(Tag(Tag::FICTIVE, false, height));
+            }
             y = ast_to_re(spec, ast->cat.ast2, ncap, height);
             y = re_cat(spec, t3, re_cat(spec, y, t4));
+
             return re_cat(spec, x, y);
         }
         case AST::TAG: {