Rename skip() to seek()

README.md

@@ -287,7 +287,9 @@ pointed by another field.
   input buffer. Can be a number, string or a function.
 
 ### saveOffset(name [,options])
-Save the current buffer offset as key `name`. This function is only useful when called after another function which would advance the internal buffer offset.
+Save the current buffer offset as key `name`. This function is only useful
+when called after another function which would advance the internal buffer
+offset.
 
 ```javascript
 var parser = new Parser()
@@ -304,14 +306,15 @@ var parser = new Parser()
   .saveOffset('currentOffset')
   // finally, use the saved offset to figure out
   // how many bytes we need to skip
-  .skip(function() {
+  .seek(function() {
     return this.seekOffset - this.currentOffset;
   })
   ... // the parser would continue here
 ```
 
-### skip(length)
-Skip `length` bytes.
+### seek(relOffset)
+Move the buffer offset for `relOffset` bytes from the current position. Use a
+negative `relOffset` value to rewind the offset. Previously named `skip(length)`.
 
 ### endianess(endianess)
 Define what endianess to use in this parser. `endianess` can be either

example/elf32.js

@@ -38,7 +38,7 @@ var ELF32SectionHeaderTable = new Parser().array('items', {
   },
 });
 
-var ELF32SectionHeaderStringTable = new Parser().skip(1).array('items', {
+var ELF32SectionHeaderStringTable = new Parser().seek(1).array('items', {
   type: new Parser().string('name', { zeroTerminated: true }),
   lengthInBytes: function(vars) {
     var shstr = vars.section_headers.items[vars.shstrndx];

example/jpg.js

@@ -82,7 +82,7 @@ var SOF0 = Parser.start()
 var Ignore = Parser.start()
   .endianess('big')
   .uint16('length')
-  .skip(function() {
+  .seek(function() {
     return this.length - 2;
   });
 

example/mbr.js

@@ -26,7 +26,7 @@ var partitionTable = new Parser()
   .uint32le('endLBA');
 
 var mbrParser = new Parser()
-  .skip(446)
+  .seek(446)
   .array('partitionTables', {
     type: partitionTable,
     length: 4,

example/tar.js

@@ -22,13 +22,13 @@ var tarHeader = new Parser()
   .string('devmajor', { length: 8, stripNull: true, formatter: oct2int })
   .string('devminor', { length: 8, stripNull: true, formatter: oct2int })
   .string('prefix', { length: 155, stripNull: true })
-  .skip(12);
+  .seek(12);
 
 var tarItem = new Parser()
   .nest({
     type: tarHeader,
   })
-  .skip(function() {
+  .seek(function() {
     return Math.ceil(this.size / 512) * 512;
   });
 

lib/binary_parser.ts

@@ -33,7 +33,7 @@ type ComplexTypes =
   | 'array'
   | 'choice'
   | 'nest'
-  | 'skip'
+  | 'seek'
   | 'pointer'
   | 'saveOffset'
   | '';
@@ -150,7 +150,7 @@ const CAPITILIZED_TYPE_NAMES: { [key in Types]: string } = {
   array: 'Array',
   choice: 'Choice',
   nest: 'Nest',
-  skip: 'Skip',
+  seek: 'Seek',
   pointer: 'Pointer',
   saveOffset: 'SaveOffset',
   '': '',
@@ -402,12 +402,16 @@ export class Parser {
     return this;
   }
 
-  skip(length: number, options: ParserOptions) {
+  skip(length: number, options?: ParserOptions) {
+    return this.seek(length, options);
+  }
+
+  seek(relOffset: number, options?: ParserOptions) {
     if (options && options.assert) {
-      throw new Error('assert option on skip is not allowed.');
+      throw new Error('assert option on seek is not allowed.');
     }
 
-    return this.setNextParser('skip', '', { length: length });
+    return this.setNextParser('seek', '', { length: relOffset });
   }
 
   string(varName: string, options: ParserOptions) {
@@ -675,8 +679,8 @@ export class Parser {
       }
       size = this.options.length * elementSize;
 
-      // if this a skip
-    } else if (this.type === 'skip') {
+      // if this a seek
+    } else if (this.type === 'seek') {
       size = this.options.length;
 
       // if this is a nested parser
@@ -753,8 +757,8 @@ export class Parser {
         case 'buffer':
           this.generateBuffer(ctx);
           break;
-        case 'skip':
-          this.generateSkip(ctx);
+        case 'seek':
+          this.generateSeek(ctx);
           break;
         case 'nest':
           this.generateNest(ctx);
@@ -874,7 +878,7 @@ export class Parser {
     }
   }
 
-  private generateSkip(ctx: Context) {
+  private generateSeek(ctx: Context) {
     const length = ctx.generateOption(this.options.length);
     ctx.pushCode(`offset += ${length};`);
   }

test/composite_parser.js

@@ -1027,7 +1027,7 @@ describe('Composite parser', function() {
         .int8('a')
         .int32le('b')
         .string('msg', { length: 10 })
-        .skip(2)
+        .seek(2)
         .array('data', {
           length: 3,
           type: 'int8',

test/primitive_parser.js

@@ -166,10 +166,10 @@ describe('Primitive parser', function() {
         big: 12345678,
       });
     });
-    it('should skip when specified', function() {
+    it('should seek offset', function() {
       var parser = Parser.start()
         .uint8('a')
-        .skip(3)
+        .seek(3)
         .uint16le('b')
         .uint32be('c');