Add KATI_foreach_sep function

syntax: $(KATI_foreach_sep var,separator,list,text)

Rather than using a space to separate items in the expanded result,
`separator` is used.

	comma := ,
	v := $(KATI_foreach_sep w,$(comma) ,a b c,"$(w)")

v will be set to: `"a", "b", "c"`

Change-Id: I426d7b24846dc495b9134319dd452809837fe5f9

5 files changed, 34 insertions, 7 deletions

diff --git a/src/expr.cc b/src/expr.cc
index 41b60bb..e3a8629 100644
--- a/src/expr.cc
+++ b/src/expr.cc
@@ -215,7 +215,7 @@ class VarSubst : public Value {
     WordWriter ww(s);
     Pattern pat(pat_str);
     for (std::string_view tok : WordScanner(value)) {
-      ww.MaybeAddWhitespace();
+      ww.MaybeAddSeparator();
       pat.AppendSubstRef(tok, subst, s);
     }
   }
diff --git a/src/func.cc b/src/func.cc
index 316e423..d5bca3a 100644
--- a/src/func.cc
+++ b/src/func.cc
@@ -108,7 +108,7 @@ void PatsubstFunc(const std::vector<Value*>& args,
   WordWriter ww(s);
   Pattern pat(pat_str);
   for (std::string_view tok : WordScanner(str)) {
-    ww.MaybeAddWhitespace();
+    ww.MaybeAddSeparator();
     pat.AppendSubst(tok, repl, s);
   }
 }
@@ -721,12 +721,30 @@ void ForeachFunc(const std::vector<Value*>& args,
     std::unique_ptr<SimpleVar> v(
         new SimpleVar(std::string(tok), VarOrigin::AUTOMATIC, nullptr, Loc()));
     ScopedGlobalVar sv(Intern(varname), v.get());
-    ww.MaybeAddWhitespace();
+    ww.MaybeAddSeparator();
     args[2]->Eval(ev, s);
   }
   ev->IncrementEvalDepth();
 }
 
+void ForeachWithSepFunc(const std::vector<Value*>& args,
+                        Evaluator* ev,
+                        std::string* s) {
+  const std::string&& varname = args[0]->Eval(ev);
+  const std::string&& separator = args[1]->Eval(ev);
+  const std::string&& list = args[2]->Eval(ev);
+  ev->DecrementEvalDepth();
+  WordWriter ww(s);
+  for (std::string_view tok : WordScanner(list)) {
+    std::unique_ptr<SimpleVar> v(
+        new SimpleVar(std::string(tok), VarOrigin::AUTOMATIC, nullptr, Loc()));
+    ScopedGlobalVar sv(Intern(varname), v.get());
+    ww.MaybeAddSeparator(separator);
+    args[3]->Eval(ev, s);
+  }
+  ev->IncrementEvalDepth();
+}
+
 void OriginFunc(const std::vector<Value*>& args,
                 Evaluator* ev,
                 std::string* s) {
@@ -1112,6 +1130,7 @@ static const std::unordered_map<std::string_view, FuncInfo> g_func_info_map = {
 
     ENTRY("KATI_extra_file_deps", &ExtraFileDepsFunc, 0, 0, false, false),
     ENTRY("KATI_shell_no_rerun", &ShellFuncNoRerun, 1, 1, false, false),
+    ENTRY("KATI_foreach_sep", &ForeachWithSepFunc, 4, 4, false, false),
 };
 
 }  // namespace
diff --git a/src/strutil.cc b/src/strutil.cc
index 0a222ad..149c729 100644
--- a/src/strutil.cc
+++ b/src/strutil.cc
@@ -83,16 +83,16 @@ void WordScanner::Split(std::vector<std::string_view>* o) {
 
 WordWriter::WordWriter(std::string* o) : out_(o), needs_space_(false) {}
 
-void WordWriter::MaybeAddWhitespace() {
+void WordWriter::MaybeAddSeparator(std::string_view sep) {
   if (needs_space_) {
-    out_->push_back(' ');
+    out_->append(sep);
   } else {
     needs_space_ = true;
   }
 }
 
 void WordWriter::Write(std::string_view s) {
-  MaybeAddWhitespace();
+  MaybeAddSeparator();
   out_->append(s);
 }
 
diff --git a/src/strutil.h b/src/strutil.h
index e199e14..bd71c1b 100644
--- a/src/strutil.h
+++ b/src/strutil.h
@@ -47,7 +47,7 @@ class WordScanner {
 class WordWriter {
  public:
   explicit WordWriter(std::string* o);
-  void MaybeAddWhitespace();
+  void MaybeAddSeparator(std::string_view sep = " ");
   void Write(std::string_view s);
 
  private:
diff --git a/testcase/foreach.mk b/testcase/foreach.mk
index 3dde97a..e1b8a00 100644
--- a/testcase/foreach.mk
+++ b/testcase/foreach.mk
@@ -1,7 +1,15 @@
 base := base
 dirs := a b c d
 dir := FAIL
+comma := ,
 files := $(foreach dir,$(dirs),$(foreach subdir,$(dirs),$(dir)/$(subdir)/$(base)))
+ifdef KATI
+files2 := $(KATI_foreach_sep dir,$(comma) ,$(dirs),"$(dir)")
+else
+# Since make doesn't have the function, manually set the result.
+files2 := "a", "b", "c", "d"
+endif
 
 test:
 	echo $(files)
+	echo $(files2)