From f59d82eb8fda3ddcf790556c6c3615e40ae8b15b Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Mon, 3 Oct 2022 21:23:22 +0300
Subject: Add support for 'for' loop second (... | for x) and third (for x
 <...) forms in script

---
 libbuild2/build/script/lexer.cxx | 31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

(limited to 'libbuild2/build/script/lexer.cxx')

diff --git a/libbuild2/build/script/lexer.cxx b/libbuild2/build/script/lexer.cxx
index d849ac9..5c13239 100644
--- a/libbuild2/build/script/lexer.cxx
+++ b/libbuild2/build/script/lexer.cxx
@@ -78,6 +78,19 @@ namespace build2
             s2 = "      ";
             break;
           }
+        case lexer_mode::for_loop:
+          {
+            // Leading tokens of the for-loop. Like command_line but
+            // recognizes colon as a separator and lsbrace like value.
+            //
+            // Note that while sensing the form of the for-loop (`for x:...`
+            // vs `for x <...`) we need to make sure that the pre-parsed token
+            // types are valid for the execution phase.
+            //
+            s1 = ":=!|&<> $(#\t\n";
+            s2 = " ==          ";
+            break;
+          }
         default:
           {
             // Recognize special variable names ($>, $<, $~).
@@ -109,6 +122,7 @@ namespace build2
         case lexer_mode::first_token:
         case lexer_mode::second_token:
         case lexer_mode::variable_line:
+        case lexer_mode::for_loop:
           r = next_line ();
           break;
         default: return base_lexer::next ();
@@ -141,7 +155,8 @@ namespace build2
         //
         if (st.lsbrace)
         {
-          assert (m == lexer_mode::variable_line);
+          assert (m == lexer_mode::variable_line ||
+                  m == lexer_mode::for_loop);
 
           state_.top ().lsbrace = false; // Note: st is a copy.
 
@@ -179,11 +194,20 @@ namespace build2
         case '(': return make_token (type::lparen);
         }
 
+        if (m == lexer_mode::for_loop)
+        {
+          switch (c)
+          {
+          case ':': return make_token (type::colon);
+          }
+        }
+
         // Command line operator/separators.
         //
         if (m == lexer_mode::command_line ||
             m == lexer_mode::first_token  ||
-            m == lexer_mode::second_token)
+            m == lexer_mode::second_token ||
+            m == lexer_mode::for_loop)
         {
           switch (c)
           {
@@ -205,7 +229,8 @@ namespace build2
         //
         if (m == lexer_mode::command_line ||
             m == lexer_mode::first_token  ||
-            m == lexer_mode::second_token)
+            m == lexer_mode::second_token ||
+            m == lexer_mode::for_loop)
         {
           if (optional<token> t = next_cmd_op (c, sep))
             return move (*t);
-- 
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