Merge pull request #578 from ethereum/fixbytedecoding

add new api function to source mapping decoder

src/util/sourceMappingDecoder.js

@@ -9,6 +9,15 @@ function SourceMappingDecoder () {
   // s:l:f:j
 }
 
+/**
+ * get a list of nodes that are at the given @arg position
+ *
+ * @param {String} astNodeType      - type of node to return
+ * @param {Int} position     - cursor position
+ * @return {Object} ast object given by the compiler
+ */
+SourceMappingDecoder.prototype.nodesAtPosition = nodesAtPosition
+
 /**
  * Decode the source mapping for the given @arg index
  *
@@ -18,6 +27,23 @@ function SourceMappingDecoder () {
  */
 SourceMappingDecoder.prototype.atIndex = atIndex
 
+/**
+ * Decode the given @arg value
+ *
+ * @param {string} value      - source location to decode ( should be start:length:file )
+ * @return {Object} returns the decompressed source mapping {start, length, file}
+ */
+SourceMappingDecoder.prototype.decode = function (value) {
+  if (value) {
+    value = value.split(':')
+    return {
+      start: parseInt(value[0]),
+      length: parseInt(value[1]),
+      file: parseInt(value[2])
+    }
+  }
+}
+
 /**
  * Decode the source mapping for the given compressed mapping
  *
@@ -139,6 +165,29 @@ function findNodeAtSourceLocation (astNodeType, sourceLocation, ast) {
   return found
 }
 
+function nodesAtPosition (astNodeType, position, ast) {
+  var astWalker = new AstWalker()
+  var callback = {}
+  var found = []
+  callback['*'] = function (node) {
+    var nodeLocation = sourceLocationFromAstNode(node)
+    if (!nodeLocation) {
+      return
+    }
+    if (nodeLocation.start <= position && nodeLocation.start + nodeLocation.length >= position) {
+      if (!astNodeType || astNodeType === node.name) {
+        found.push(node)
+        if (astNodeType) return false
+      }
+      return true
+    } else {
+      return false
+    }
+  }
+  astWalker.walk(ast.AST, callback)
+  return found
+}
+
 function atIndex (index, mapping) {
   var ret = {}
   var map = mapping.split(';')