Enable Strings as choice keys

README.md

@@ -151,6 +151,8 @@ Parse bytes as an array. `options` is an object; following options are available
 	Use number for statically sized arrays.
 - `readUntil` - (either `length` or `readUntil` is required) If `'eof'`, then this parser
 	reads until the end of `Buffer` object. If function it reads until the function returns true.
+- `$parent` - (Optional) An array with selected properties from the parental scope. References can be
+  accessed inside functions using `this.$parent[...]`.
 
 ```javascript
 var parser = new Parser()
@@ -193,9 +195,11 @@ Combining `choice` with `array` is useful for parsing a typical
 
 - `tag` - (Required) The value used to determine which parser to use from the `choices`
 	Can be a string pointing to another field or a function.
-- `choices` - (Required) An object which key is an integer and value is the parser which is executed
+- `choices` - (Required) An object which key is an integer/string and value is the parser which is executed
 	when `tag` equals the key value.
 - `defaultChoice` - (Optional) In case of the tag value doesn't match any of `choices` use this parser.
+- `$parent` - (Optional) An array with selected properties from the parental scope. References can be
+accessed inside functions using `this.$parent[...]`.
 
 ```javascript
 var parser1 = ...;
@@ -221,7 +225,7 @@ Nest a parser in this position. Parse result of the nested parser is stored in t
 - `type` - (Required) A `Parser` object.
 
 ### skip(length)
-Skip parsing for `length` bytes.
+Skip parsing of bytes. `length` can be either a number, a string or a function.
 
 ### endianess(endianess)
 Define what endianess to use in this parser. `endianess` can be either `'little'` or `'big'`.
@@ -254,7 +258,7 @@ These are common options that can be specified in all parsers.
 ```javascript
 var parser = new Parser()
   .array('ipv4', {
-    type: uint8,
+    type: 'uint8',
     length: '4',
     formatter: function(arr) { return arr.join('.'); }
   });

lib/binary_parser.js

@@ -148,9 +148,6 @@ Parser.prototype.choice = function(varName, options) {
         throw new Error('Choices option of array is not defined.');
     }
     Object.keys(options.choices).forEach(function(key) {
-        if (isNaN(parseInt(key, 10))) {
-            throw new Error('Key of choices must be a number.');
-        }
         if (!options.choices[key]) {
             throw new Error('Choice Case ' + key + ' of ' + varName + ' is not valid.');
         }
@@ -485,7 +482,17 @@ Parser.prototype.generateArray = function(ctx) {
         ctx.pushCode('var {0} = buffer.read{1}(offset);', item, NAME_MAP[type]);
         ctx.pushCode('offset += {0};', PRIMITIVE_TYPES[NAME_MAP[type]]);
     } else if (type instanceof Parser) {
-        ctx.pushCode('var {0} = {};', item);
+        if (!this.options.$parent) {
+            ctx.pushCode('var {0} = {};', item);
+        } else {
+          	ctx.pushCode('var {0} = { "$parent": {1} };', item,
+            		'[' + this.options.$parent.map(function(prop){ return '"' + prop + '"'; }).toString() +
+            		'].reduce(function($parent, key){\
+            		    $parent[key] = ' + ctx.generateVariable() + '[key];\
+            		    return $parent;\
+            		}, {})'
+          	);
+        }
 
         ctx.pushScope(item);
         type.generate(ctx);
@@ -519,12 +526,22 @@ Parser.prototype.generateChoiceCase = function(ctx, varName, type) {
 Parser.prototype.generateChoice = function(ctx) {
     var tag = ctx.generateOption(this.options.tag);
 
-    ctx.pushCode('{0} = {};', ctx.generateVariable(this.varName));
+    if (!this.options.$parent) {
+        ctx.pushCode('{0} = {};', ctx.generateVariable(this.varName));
+    } else {
+      	ctx.pushCode('{0} = { "$parent": {1} };', ctx.generateVariable(this.varName),
+        		'[' + this.options.$parent.map(function(prop){ return '"' + prop + '"'; }).toString() +
+        		'].reduce(function($parent, key){\
+        		    $parent[key] = ' + ctx.generateVariable() + '[key];\
+        		    return $parent;\
+        		}, {})'
+      	);
+    }
     ctx.pushCode('switch({0}) {', tag);
     Object.keys(this.options.choices).forEach(function(tag) {
         var type = this.options.choices[tag];
 
-        ctx.pushCode('case {0}:', tag);
+        ctx.pushCode('case ' + (isNaN(tag) ? '"{0}"' : '{0}') + ':', tag);
         this.generateChoiceCase(ctx, this.varName, type);
         ctx.pushCode('break;');
     }, this);