From 7bcae8f6a80a917e5295548ae1ddf652b2303ca1 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Wed, 9 Nov 2016 20:25:20 -0800
Subject: [PATCH] :art: flatten_grammar

---
 .../prepare_grammar/flatten_grammar_spec.cc   | 56 +++++++++----------
 .../prepare_grammar/flatten_grammar.cc        |  6 +-
 2 files changed, 29 insertions(+), 33 deletions(-)

diff --git a/spec/compiler/prepare_grammar/flatten_grammar_spec.cc b/spec/compiler/prepare_grammar/flatten_grammar_spec.cc
index 80fe1332..eab2b61c 100644
--- a/spec/compiler/prepare_grammar/flatten_grammar_spec.cc
+++ b/spec/compiler/prepare_grammar/flatten_grammar_spec.cc
@@ -6,9 +6,8 @@
 #include "helpers/rule_helpers.h"
 
 template<typename T, typename Func>
-std::vector<typename std::result_of<Func(T)>::type>
-collect(const std::vector<T> &v, Func f) {
-  vector<typename std::result_of<Func(T)>::type> result;
+vector<typename result_of<Func(T)>::type> collect(const vector<T> &v, Func f) {
+  vector<typename result_of<Func(T)>::type> result;
   for (const T &item : v)
     result.push_back(f(item));
   return result;
@@ -21,6 +20,30 @@ using prepare_grammar::flatten_grammar;
 using prepare_grammar::InitialSyntaxGrammar;
 
 describe("flatten_grammar", []() {
+  auto get_symbol_sequences = [&](vector<Production> productions) {
+    return collect(productions, [](Production p) {
+      return collect(p, [](ProductionStep e) {
+        return e.symbol;
+      });
+    });
+  };
+
+  auto get_precedence_sequences = [&](vector<Production> productions) {
+    return collect(productions, [](Production p) {
+      return collect(p, [](ProductionStep e) {
+        return e.precedence;
+      });
+    });
+  };
+
+  auto get_associativity_sequences = [&](vector<Production> productions) {
+    return collect(productions, [](Production p) {
+      return collect(p, [](ProductionStep e) {
+        return e.associativity;
+      });
+    });
+  };
+
   InitialSyntaxGrammar input_grammar{{
 
     // Choices within rules are extracted, resulting in multiple productions.
@@ -59,35 +82,10 @@ describe("flatten_grammar", []() {
         i_sym(4),
       })),
     }))
-
   }, {}, {}};
 
   SyntaxGrammar grammar = flatten_grammar(input_grammar);
 
-  auto get_symbol_sequences = [&](vector<Production> productions) {
-    return collect(productions, [](Production p) {
-      return collect(p, [](ProductionStep e) {
-        return e.symbol;
-      });
-    });
-  };
-
-  auto get_precedence_sequences = [&](vector<Production> productions) {
-    return collect(productions, [](Production p) {
-      return collect(p, [](ProductionStep e) {
-        return e.precedence;
-      });
-    });
-  };
-
-  auto get_associativity_sequences = [&](vector<Production> productions) {
-    return collect(productions, [](Production p) {
-      return collect(p, [](ProductionStep e) {
-        return e.associativity;
-      });
-    });
-  };
-
   it("preserves the names and types of the grammar's variables", [&]() {
     AssertThat(grammar.variables[0].name, Equals("variable0"));
     AssertThat(grammar.variables[1].name, Equals("variable1"));
@@ -142,7 +140,7 @@ describe("flatten_grammar", []() {
       })));
   });
 
-  it("associates each symbol with the correct associativity annotation", [&]() {
+  it("associates each symbol with the correct associativity", [&]() {
     Associativity none = AssociativityNone;
 
     AssertThat(
diff --git a/src/compiler/prepare_grammar/flatten_grammar.cc b/src/compiler/prepare_grammar/flatten_grammar.cc
index a84cd43e..76b6e769 100644
--- a/src/compiler/prepare_grammar/flatten_grammar.cc
+++ b/src/compiler/prepare_grammar/flatten_grammar.cc
@@ -1,5 +1,4 @@
 #include "compiler/prepare_grammar/flatten_grammar.h"
-#include <string>
 #include <vector>
 #include <algorithm>
 #include "compiler/prepare_grammar/extract_choices.h"
@@ -14,7 +13,6 @@ namespace tree_sitter {
 namespace prepare_grammar {
 
 using std::find;
-using std::string;
 using std::vector;
 
 class FlattenRule : public rules::RuleFn<void> {
@@ -81,8 +79,8 @@ SyntaxGrammar flatten_grammar(const InitialSyntaxGrammar &grammar) {
     vector<Production> productions;
     for (const rule_ptr &rule_component : extract_choices(variable.rule)) {
       Production production = FlattenRule().flatten(rule_component);
-      if (std::find(productions.begin(), productions.end(), production) ==
-          productions.end())
+      auto end = productions.end();
+      if (find(productions.begin(), end, production) == end)
         productions.push_back(production);
     }
     result.variables.push_back(