Fix #272 by moving template code around

A lot of template bloat was being generated by having map, filter and
countUntil inside the 'and' and 'or' templates.

By simply moving them outside compilation speed and memory is back to normal
again.

Author: skoppe

pegged/peg.d

@@ -1332,7 +1332,7 @@ template and(rules...) if (rules.length > 0)
             }
             else
             {
-                auto firstLongestFailedMatch = result.children.countUntil!(c => c.failEnd > temp.end);
+                auto firstLongestFailedMatch = result.children.firstLongestFailedMatch(temp.end);
                 if (firstLongestFailedMatch == -1) {
                     result.children ~= temp;// add the failed node, to indicate which failed
                     if (temp.matches.length > 0)
@@ -1345,8 +1345,8 @@ template and(rules...) if (rules.length > 0)
                     // so that it is no longer successful and we want to move its failedChild into its children.
                     failedChildFixup(result.children[firstLongestFailedMatch], result.children[firstLongestFailedMatch].failEnd);
                 }
-                result.end = result.children.map!(c => c.end).maxElement;
-                result.failEnd = result.children.map!(c => c.failEnd).maxElement;
+                result.end = result.children.maxEnd();
+                result.failEnd = result.children.maxFailEnd();
                 version (tracer)
                 {
                     if (shouldTrace(getName!(r)(), p))
@@ -1380,33 +1380,54 @@ template and(rules...) if (rules.length > 0)
         return name;
     }
 
-    // A child ParseTree has kept track of an alternate ParseTree (in failedChild) that matches longer.
-    // whenever the 'and' rule fails we want to rewrite that child so that the failedChild is
-    // moved into its children, the successful is set to false, the end is set the its failEnd,
-    // the failEnd is reset, and all that info is propagated upwards the tree so intermediate
-    // nodes reflect the proper state.
-    bool failedChildFixup(ref ParseTree p, size_t failEnd) {
-        if (p.failedChild.length > 0) {
-            p.children ~= p.failedChild[0];
-            p.failedChild = [];
-            p.successful = false;
-            p.end = p.failEnd;
-            p.failEnd = p.children.map!(c => c.failEnd).maxElement();
-            return true;
-        } else {
-            bool result = false;
-            foreach(ref c; p.children) {
-                if (c.failEnd != failEnd)
-                    continue;
-                if (failedChildFixup(c, failEnd)) {
-                    p.end = c.end;
-                    p.successful = false;
-                    p.failEnd = p.children.map!(c => c.failEnd).maxElement();
-                    result = true;
-                }
+}
+
+auto firstLongestFailedMatch(ParseTree[] children, size_t threshold) {
+    return children.countUntil!(c => c.failEnd > threshold);
+}
+
+auto maxFailEnd(ParseTree[] children)
+{
+    return children.map!(c => c.failEnd).maxElement;
+}
+
+auto maxEnd(ParseTree[] children)
+{
+    return children.map!(c => c.end).maxElement;
+}
+
+// A child ParseTree has kept track of an alternate ParseTree (in failedChild) that matches longer.
+// whenever the 'and' rule fails we want to rewrite that child so that the failedChild is
+// moved into its children, the successful is set to false, the end is set the its failEnd,
+// the failEnd is reset, and all that info is propagated upwards the tree so intermediate
+// nodes reflect the proper state.
+bool failedChildFixup(ref ParseTree p, size_t failEnd)
+{
+    if (p.failedChild.length > 0)
+    {
+        p.children ~= p.failedChild[0];
+        p.failedChild = [];
+        p.successful = false;
+        p.end = p.failEnd;
+        p.failEnd = p.children.map!(c => c.failEnd).maxElement();
+        return true;
+    }
+    else
+    {
+        bool result = false;
+        foreach (ref c; p.children)
+        {
+            if (c.failEnd != failEnd)
+                continue;
+            if (failedChildFixup(c, failEnd))
+            {
+                p.end = c.end;
+                p.successful = false;
+                p.failEnd = p.children.map!(c => c.failEnd).maxElement();
+                result = true;
             }
-            return result;
         }
+        return result;
     }
 }
 
@@ -1725,8 +1746,8 @@ template or(rules...) if (rules.length > 0)
         longestFail.matches = longestFail.matches.length == 0 ? [orErrorString] :
                               longestFail.matches[0..$-1]  // discarding longestFail error message
                             ~ [orErrorString];             // and replacing it by the new, concatenated one.
-        auto children = results[].filter!(r => max(r.end, r.failEnd) >= maxFailedLength).array();
-        return ParseTree(name, false, longestFail.matches, p.input, p.end, longestFail.end, children, children.map!(c => c.failEnd).maxElement);
+        auto children = results[].getUpto(maxFailedLength);
+        return ParseTree(name, false, longestFail.matches, p.input, p.end, longestFail.end, children, children.maxFailEnd);
     }
 
     ParseTree or(string input)
@@ -1740,6 +1761,10 @@ template or(rules...) if (rules.length > 0)
     }
 }
 
+auto getUpto(ParseTree[] children, size_t minFailedLength) {
+    return children.filter!(r => max(r.end, r.failEnd) >= minFailedLength).array();
+}
+
 unittest // 'or' unit test
 {
     alias charRange!('a','b') ab;