immediately evaluate variables in top-level bindings

3 files changed, 20 insertions, 6 deletions

diff --git a/src/parsers.cc b/src/parsers.cc
index 8408195..4f19046 100644
--- a/src/parsers.cc
+++ b/src/parsers.cc
@@ -254,7 +254,7 @@ bool ManifestParser::Parse(const string& input, string* err) {
         break;
       case Token::IDENT: {
         string name, value;
-        if (!ParseLet(&name, &value, err))
+        if (!ParseLet(&name, &value, true, err))
           return false;
         if (value.substr(0, 9) == "ROOT_HACK") {
           // XXX remove this hack, or make it more principled.
@@ -302,7 +302,7 @@ bool ManifestParser::ParseRule(string* err) {
 
     while (tokenizer_.PeekToken() != Token::OUTDENT) {
       string key, val;
-      if (!ParseLet(&key, &val, err))
+      if (!ParseLet(&key, &val, false, err))
         return false;
 
       string parse_err;
@@ -331,7 +331,8 @@ bool ManifestParser::ParseRule(string* err) {
   return true;
 }
 
-bool ManifestParser::ParseLet(string* name, string* value, string* err) {
+bool ManifestParser::ParseLet(string* name, string* value, bool expand,
+                              string* err) {
   if (!tokenizer_.ReadIdent(name))
     return tokenizer_.Error("expected variable name", err);
   if (!tokenizer_.ExpectToken(Token::EQUALS, err))
@@ -342,6 +343,14 @@ bool ManifestParser::ParseLet(string* name, string* value, string* err) {
   if (!tokenizer_.ReadToNewline(value, err))
     return false;
 
+  if (expand) {
+    EvalString eval;
+    string eval_err;
+    if (!eval.Parse(*value, &eval_err))
+      return tokenizer_.Error(eval_err, err);
+    *value = eval.Evaluate(env_);
+  }
+
   return true;
 }
 
@@ -427,7 +436,7 @@ bool ManifestParser::ParseEdge(string* err) {
     env->parent_ = env_;
     while (tokenizer_.PeekToken() != Token::OUTDENT) {
       string key, val;
-      if (!ParseLet(&key, &val, err))
+      if (!ParseLet(&key, &val, false, err))
         return false;
       env->AddBinding(key, val);
     }
diff --git a/src/parsers.h b/src/parsers.h
index 2655ce8..fc09cce 100644
--- a/src/parsers.h
+++ b/src/parsers.h
@@ -83,7 +83,9 @@ struct ManifestParser {
   bool Parse(const string& input, string* err);
 
   bool ParseRule(string* err);
-  bool ParseLet(string* key, string* val, string* err);
+  // Parse a key=val statement.  If expand is true, evaluate variables
+  // within the value immediately.
+  bool ParseLet(string* key, string* val, bool expand, string* err);
   bool ParseEdge(string* err);
   bool ParseSubNinja(string* err);
 
diff --git a/src/parsers_test.cc b/src/parsers_test.cc
index 8187a62..58e40b8 100644
--- a/src/parsers_test.cc
+++ b/src/parsers_test.cc
@@ -57,12 +57,15 @@ TEST_F(ParserTest, Variables) {
 "\n"
 "extra = -pthread\n"
 "with_under = -under\n"
-"build a: link b c\n"));
+"build a: link b c\n"
+"nested1 = 1\n"
+"nested2 = $nested1/2\n"));
 
   ASSERT_EQ(1, state.edges_.size());
   Edge* edge = state.edges_[0];
   EXPECT_EQ("ld one-letter-test -pthread -under -o a b c",
             edge->EvaluateCommand());
+  EXPECT_EQ("1/2", state.bindings_.LookupVariable("nested2"));
 }
 
 TEST_F(ParserTest, VariableScope) {