jspatch refactor for programmability

Factor out the getPatternFromPatch and getPatchedCode, useful for integration
with other tools.

bin/jspatch-cli.js

@@ -94,30 +94,15 @@ var matchFn;
 function processPatch(patchSource, patchFilename) {
   var lineNumber = 1;
   var chunks = _.map(patchSource.split('\n---\n'), function(chunkSource) {
-    var lines = chunkSource.split('\n');
     var chunk = {
-      find: [],
+      find: jsgrep.Matcher.getPatternFromPatch(chunkSource),
       patch: chunkSource,
       filename: patchFilename || "",
       lineNumber: lineNumber
     };
 
-    for(var i = 0; i < lines.length; i++) {
-      if (lines[i][0] == '-') {
-        chunk.find.push(lines[i].substr(1));
+    lineNumber += chunkSource.split('\n').length + 1;
 
-      } else if (lines[i][0] == '+') {
-        // So line numbers match up
-        chunk.find.push('\n');
-
-      } else {
-        chunk.find.push(lines[i]);
-      }
-    }
-
-    chunk.find = chunk.find.join('\n').trim();
-
-    lineNumber += lines.length + 1;
     return chunk;
   });
 

lib/jsgrep.js

@@ -62,6 +62,25 @@ Matcher.getSourceForNode = function(target) {
   return target.tokenizer.source.substring(start, end);
 };
 
+Matcher.getPatternFromPatch = function(patch) {
+  var pattern = [];
+  var lines = patch.split('\n');
+  for(var i = 0; i < lines.length; i++) {
+    if (lines[i][0] == '-') {
+      pattern.push(lines[i].substr(1));
+
+    } else if (lines[i][0] == '+') {
+      // So line numbers match up
+      pattern.push('\n');
+
+    } else {
+      pattern.push(lines[i]);
+    }
+  }
+
+  return pattern.join('\n');
+};
+
 Matcher.prototype.find = function(pattern, callback, options) {
   var ret = [ ];
   var self = this;
@@ -88,10 +107,10 @@ Matcher.prototype.matchStrict = function(pattern, callback) {
 };
 
 /**
- * Apply a single patch chunk to this matcher's node. The matcher must strictly
- * match the patch!
+ * Return the results of applying a single patch chunk to this matcher's node.
+ * The matcher must strictly match the patch!
  */
-Matcher.prototype.applyPatch = function(patch, filename, line) {
+Matcher.prototype.getPatchedCode = function(patch, filename, line) {
   const tokens = Narcissus.definitions.tokenIds;
   const REMOVE = '!REMOVE';
   const ADD = '!ADD';
@@ -249,6 +268,15 @@ Matcher.prototype.applyPatch = function(patch, filename, line) {
   // Remove blank lines from new code
   nodeSource = nodeSource.replace(/^\s*\n|\n*$/g, '');
 
+  return nodeSource;
+}
+
+/**
+ * Apply a single patch chunk to this matcher's node. The matcher must strictly
+ * match the patch!
+ */
+Matcher.prototype.applyPatch = function(patch, filename, line) {
+  var nodeSource = this.getPatchedCode(patch, filename, line);
   this._replaceWithString(this.ast, nodeSource);
 };