[C++] Refactor pattern functions in strutil

5 files changed, 60 insertions, 39 deletions

diff --git a/func.cc b/func.cc
index 9e33f35..a47d55f 100644
--- a/func.cc
+++ b/func.cc
@@ -20,13 +20,14 @@
 namespace {
 
 void PatsubstFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
-  shared_ptr<string> pat = args[0]->Eval(ev);
+  shared_ptr<string> pat_str = args[0]->Eval(ev);
   shared_ptr<string> repl = args[1]->Eval(ev);
   shared_ptr<string> str = args[2]->Eval(ev);
   WordWriter ww(s);
+  Pattern pat(*pat_str);
   for (StringPiece tok : WordScanner(*str)) {
     ww.MaybeAddWhitespace();
-    AppendSubstPattern(tok, *pat, *repl, s);
+    pat.AppendSubst(tok, *repl, s);
   }
 }
 
@@ -64,12 +65,14 @@ void FindstringFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
 void FilterFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
   shared_ptr<string> pat_buf = args[0]->Eval(ev);
   shared_ptr<string> text = args[1]->Eval(ev);
-  vector<StringPiece> pats;
-  WordScanner(*pat_buf).Split(&pats);
+  vector<Pattern> pats;
+  for (StringPiece pat : WordScanner(*pat_buf)) {
+    pats.push_back(Pattern(pat));
+  }
   WordWriter ww(s);
   for (StringPiece tok : WordScanner(*text)) {
-    for (StringPiece pat : pats) {
-      if (MatchPattern(tok, pat)) {
+    for (const Pattern& pat : pats) {
+      if (pat.Match(tok)) {
         ww.Write(tok);
         break;
       }
@@ -80,13 +83,15 @@ void FilterFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
 void FilterOutFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
   shared_ptr<string> pat_buf = args[0]->Eval(ev);
   shared_ptr<string> text = args[1]->Eval(ev);
-  vector<StringPiece> pats;
-  WordScanner(*pat_buf).Split(&pats);
+  vector<Pattern> pats;
+  for (StringPiece pat : WordScanner(*pat_buf)) {
+    pats.push_back(Pattern(pat));
+  }
   WordWriter ww(s);
   for (StringPiece tok : WordScanner(*text)) {
     bool matched = false;
-    for (StringPiece pat : pats) {
-      if (MatchPattern(tok, pat)) {
+    for (const Pattern& pat : pats) {
+      if (pat.Match(tok)) {
         matched = true;
         break;
       }
diff --git a/strutil.cc b/strutil.cc
index f76a2ab..03eeb49 100644
--- a/strutil.cc
+++ b/strutil.cc
@@ -133,11 +133,25 @@ StringPiece TrimSuffix(StringPiece str, StringPiece suffix) {
   return str.substr(0, size_diff);
 }
 
-void AppendSubstPattern(StringPiece str, StringPiece pat, StringPiece subst,
-                        string* out) {
-  size_t pat_percent_index = pat.find('%');
-  if (pat_percent_index == string::npos) {
-    if (str == pat) {
+Pattern::Pattern(StringPiece pat)
+    : pat_(pat), percent_index_(pat.find('%')) {
+}
+
+bool Pattern::Match(StringPiece str) const {
+  if (percent_index_ == string::npos)
+    return str == pat_;
+  return MatchImpl(str);
+}
+
+bool Pattern::MatchImpl(StringPiece str) const {
+  return (HasPrefix(str, pat_.substr(0, percent_index_)) &&
+          HasSuffix(str, pat_.substr(percent_index_ + 1)));
+}
+
+void Pattern::AppendSubst(StringPiece str, StringPiece subst,
+                          string* out) const {
+  if (percent_index_ == string::npos) {
+    if (str == pat_) {
       AppendString(subst, out);
       return;
     } else {
@@ -146,16 +160,15 @@ void AppendSubstPattern(StringPiece str, StringPiece pat, StringPiece subst,
     }
   }
 
-  if (HasPrefix(str, pat.substr(0, pat_percent_index)) &&
-      HasSuffix(str, pat.substr(pat_percent_index + 1))) {
+  if (MatchImpl(str)) {
     size_t subst_percent_index = subst.find('%');
     if (subst_percent_index == string::npos) {
       AppendString(subst, out);
       return;
     } else {
       AppendString(subst.substr(0, subst_percent_index), out);
-      AppendString(str.substr(pat_percent_index,
-                              str.size() - pat.size() + 1), out);
+      AppendString(str.substr(percent_index_,
+                              str.size() - pat_.size() + 1), out);
       AppendString(subst.substr(subst_percent_index + 1), out);
       return;
     }
@@ -163,24 +176,17 @@ void AppendSubstPattern(StringPiece str, StringPiece pat, StringPiece subst,
   AppendString(str, out);
 }
 
-void AppendSubstRef(StringPiece str, StringPiece pat, StringPiece subst,
-                    string* out) {
-  if (pat.find('%') != string::npos && subst.find('%') != string::npos) {
-    AppendSubstPattern(str, pat, subst, out);
+void Pattern::AppendSubstRef(StringPiece str, StringPiece subst,
+                             string* out) const {
+  if (percent_index_ != string::npos && subst.find('%') != string::npos) {
+    AppendSubst(str, subst, out);
     return;
   }
-  StringPiece s = TrimSuffix(str, pat);
+  StringPiece s = TrimSuffix(str, pat_);
   out->append(s.begin(), s.end());
   out->append(subst.begin(), subst.end());
 }
 
-bool MatchPattern(StringPiece str, StringPiece pat) {
-  size_t i = pat.find('%');
-  if (i == string::npos)
-    return str == pat;
-  return HasPrefix(str, pat.substr(0, i)) && HasSuffix(str, pat.substr(i+1));
-}
-
 string NoLineBreak(const string& s) {
   size_t index = s.find('\n');
   if (index == string::npos)
diff --git a/strutil.h b/strutil.h
index d7c3785..c0d040f 100644
--- a/strutil.h
+++ b/strutil.h
@@ -79,13 +79,22 @@ bool HasSuffix(StringPiece str, StringPiece suffix);
 
 StringPiece TrimSuffix(StringPiece str, StringPiece suffix);
 
-void AppendSubstPattern(StringPiece str, StringPiece pat, StringPiece subst,
-                        string* out);
+class Pattern {
+ public:
+  explicit Pattern(StringPiece pat);
+
+  bool Match(StringPiece str) const;
+
+  void AppendSubst(StringPiece str, StringPiece subst, string* out) const;
 
-void AppendSubstRef(StringPiece str, StringPiece pat, StringPiece subst,
-                    string* out);
+  void AppendSubstRef(StringPiece str, StringPiece subst, string* out) const;
 
-bool MatchPattern(StringPiece str, StringPiece pat);
+ private:
+  bool MatchImpl(StringPiece str) const;
+
+  StringPiece pat_;
+  size_t percent_index_;
+};
 
 string NoLineBreak(const string& s);
 
diff --git a/strutil_test.cc b/strutil_test.cc
index f08c07d..d014c88 100644
--- a/strutil_test.cc
+++ b/strutil_test.cc
@@ -36,7 +36,7 @@ void TestHasSuffix() {
 
 string SubstPattern(StringPiece str, StringPiece pat, StringPiece subst) {
   string r;
-  AppendSubstPattern(str, pat, subst, &r);
+  Pattern(pat).AppendSubst(str, subst, &r);
   return r;
 }
 
diff --git a/value.cc b/value.cc
index 3dd6e80..bb19fca 100644
--- a/value.cc
+++ b/value.cc
@@ -148,12 +148,13 @@ class VarSubst : public Value {
     shared_ptr<string> name = name_->Eval(ev);
     Var* v = ev->LookupVar(*name);
     shared_ptr<string> value = v->Eval(ev);
-    shared_ptr<string> pat = pat_->Eval(ev);
+    shared_ptr<string> pat_str = pat_->Eval(ev);
     shared_ptr<string> subst = subst_->Eval(ev);
     WordWriter ww(s);
+    Pattern pat(*pat_str);
     for (StringPiece tok : WordScanner(*value)) {
       ww.MaybeAddWhitespace();
-      AppendSubstRef(tok, *pat, *subst, s);
+      pat.AppendSubstRef(tok, *subst, s);
     }
   }