From aa1a2e74cfce13e543793b264c7d911c43626e32 Mon Sep 17 00:00:00 2001
From: David Majda <david@majda.cz>
Date: Thu, 1 Sep 2016 13:55:41 +0200
Subject: [PATCH] Replace suitable for loops with Array methods (in /examples)

See #441.
---
 examples/arithmetics.pegjs | 24 +++++++--------------
 examples/css.pegjs         | 26 +++++++----------------
 examples/javascript.pegjs  | 43 ++++++++++----------------------------
 examples/json.pegjs        | 10 ++++-----
 4 files changed, 31 insertions(+), 72 deletions(-)

diff --git a/examples/arithmetics.pegjs b/examples/arithmetics.pegjs
index e7bdc44..5cd36cf 100644
--- a/examples/arithmetics.pegjs
+++ b/examples/arithmetics.pegjs
@@ -7,26 +7,18 @@
 
 Expression
   = head:Term tail:(_ ("+" / "-") _ Term)* {
-      var result = head, i;
-
-      for (i = 0; i < tail.length; i++) {
-        if (tail[i][1] === "+") { result += tail[i][3]; }
-        if (tail[i][1] === "-") { result -= tail[i][3]; }
-      }
-
-      return result;
+      return tail.reduce(function(result, element) {
+        if (element[1] === "+") { return result + element[3]; }
+        if (element[1] === "-") { return result - element[3]; }
+      }, head);
     }
 
 Term
   = head:Factor tail:(_ ("*" / "/") _ Factor)* {
-      var result = head, i;
-
-      for (i = 0; i < tail.length; i++) {
-        if (tail[i][1] === "*") { result *= tail[i][3]; }
-        if (tail[i][1] === "/") { result /= tail[i][3]; }
-      }
-
-      return result;
+      return tail.reduce(function(result, element) {
+        if (element[1] === "*") { return result * element[3]; }
+        if (element[1] === "/") { return result / element[3]; }
+      }, head);
     }
 
 Factor
diff --git a/examples/css.pegjs b/examples/css.pegjs
index 60e26d0..0a6895d 100644
--- a/examples/css.pegjs
+++ b/examples/css.pegjs
@@ -25,15 +25,9 @@
   }
 
   function extractList(list, index) {
-    var result = [], i;
-
-    for (i = 0; i < list.length; i++) {
-      if (list[i][index] !== null) {
-        result.push(list[i][index]);
-      }
-    }
-
-    return result;
+    return list
+      .map(function(element) { return element[index]; })
+      .filter(function(element) { return element !== null; });
   }
 
   function buildList(head, tail, index) {
@@ -41,18 +35,14 @@
   }
 
   function buildExpression(head, tail) {
-    var result = head, i;
-
-    for (i = 0; i < tail.length; i++) {
-      result = {
+    return tail.reduce(function(result, element) {
+      return {
         type:     "Expression",
-        operator: tail[i][0],
+        operator: element[0],
         left:     result,
-        right:    tail[i][1]
+        right:    element[1]
       };
-    }
-
-    return result;
+    }, head);
   }
 }
 
diff --git a/examples/javascript.pegjs b/examples/javascript.pegjs
index e39babe..3ca4fc3 100644
--- a/examples/javascript.pegjs
+++ b/examples/javascript.pegjs
@@ -39,13 +39,8 @@
   };
 
   function filledArray(count, value) {
-    var result = new Array(count), i;
-
-    for (i = 0; i < count; i++) {
-      result[i] = value;
-    }
-
-    return result;
+    return Array.apply(null, new Array(count))
+      .map(function() { return value; });
   }
 
   function extractOptional(optional, index) {
@@ -53,49 +48,33 @@
   }
 
   function extractList(list, index) {
-    var result = new Array(list.length), i;
-
-    for (i = 0; i < list.length; i++) {
-      result[i] = list[i][index];
-    }
-
-    return result;
+    return list.map(function(element) { return element[index]; });
   }
 
   function buildList(head, tail, index) {
     return [head].concat(extractList(tail, index));
   }
 
-  function buildTree(head, tail, builder) {
-    var result = head, i;
-
-    for (i = 0; i < tail.length; i++) {
-      result = builder(result, tail[i]);
-    }
-
-    return result;
-  }
-
   function buildBinaryExpression(head, tail) {
-    return buildTree(head, tail, function(result, element) {
+    return tail.reduce(function(result, element) {
       return {
         type:     "BinaryExpression",
         operator: element[1],
         left:     result,
         right:    element[3]
       };
-    });
+    }, head);
   }
 
   function buildLogicalExpression(head, tail) {
-    return buildTree(head, tail, function(result, element) {
+    return tail.reduce(function(result, element) {
       return {
         type:     "LogicalExpression",
         operator: element[1],
         left:     result,
         right:    element[3]
       };
-    });
+    }, head);
   }
 
   function optionalList(value) {
@@ -639,14 +618,14 @@ MemberExpression
         }
     )*
     {
-      return buildTree(head, tail, function(result, element) {
+      return tail.reduce(function(result, element) {
         return {
           type:     "MemberExpression",
           object:   result,
           property: element.property,
           computed: element.computed
         };
-      });
+      }, head);
     }
 
 NewExpression
@@ -681,11 +660,11 @@ CallExpression
         }
     )*
     {
-      return buildTree(head, tail, function(result, element) {
+      return tail.reduce(function(result, element) {
         element[TYPES_TO_PROPERTY_NAMES[element.type]] = result;
 
         return element;
-      });
+      }, head);
     }
 
 Arguments
diff --git a/examples/json.pegjs b/examples/json.pegjs
index d0ba9f4..e0afbbf 100644
--- a/examples/json.pegjs
+++ b/examples/json.pegjs
@@ -52,13 +52,11 @@ object
       head:member
       tail:(value_separator m:member { return m; })*
       {
-        var result = {}, i;
+        var result = {};
 
-        result[head.name] = head.value;
-
-        for (i = 0; i < tail.length; i++) {
-          result[tail[i].name] = tail[i].value;
-        }
+        [head].concat(tail).forEach(function(element) {
+          result[element.name] = element.value;
+        });
 
         return result;
       }