Start on Snippets extension

Can parse a basic snippets file

spec/extensions/snippets-spec.coffee

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+Snippets = require 'snippets'
+Buffer = require 'buffer'
+Editor = require 'editor'
+_ = require 'underscore'
+
+fdescribe "Snippets extension", ->
+  [buffer, editor] = []
+  beforeEach ->
+    buffer = new Buffer(require.resolve('fixtures/sample.js'))
+    editor = new Editor({buffer})
+
+  describe "when 'tab' is triggered on the editor", ->
+    describe "when the letters preceding the cursor are registered as a global extension", ->
+      it "replaces the prefix with the snippet text", ->
+        Snippets.evalSnippets 'js', """
+          snippet te "Test snippet description"
+          this is a test
+          endsnippet
+
+          snippet moo "Moo snippet"
+          Mooooooo!
+          endsnippet
+        """
+
+        editor.insertText("te")
+        editor.trigger 'tab'
+
+        expect(editor.getCursorScreenPosition()).toEqual [0, 2]
+        expect(buffer.lineForRow(0)).toBe "this is a testvar quicksort = function () {"
+
+  ffdescribe "Snippets parser", ->
+    it "can parse a snippet", ->
+      snippets = Snippets.snippetsParser.parse """
+        snippet te "Test snippet description"
+        this is a test
+        endsnippet
+      """
+
+      expect(_.keys(snippets).length).toBe 1
+      snippet = snippets['te']
+      expect(snippet.prefix).toBe 'te'
+      expect(snippet.description).toBe "Test snippet description"
+      expect(snippet.body).toBe "this is a test"

src/extensions/snippets/index.coffee

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+module.exports = require 'extensions/snippets/snippets.coffee'

src/extensions/snippets/snippets.coffee

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+fs = require 'fs'
+PEG = require 'pegjs'
+
+module.exports =
+  snippetsByExtension: {}
+  snippetsParser: PEG.buildParser(fs.read(require.resolve 'extensions/snippets/snippets.pegjs'))
+
+  evalSnippets: (extension, text) ->
+    @snippetsByExtension[extension] = snippetsParser.parse(text)
+

src/extensions/snippets/snippets.pegjs

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+snippets = snippets:snippet+ {
+  var snippetsByPrefix = {};
+  snippets.forEach(function(snippet) {
+    snippetsByPrefix[snippet.prefix] = snippet
+  });
+  return snippetsByPrefix;
+}
+
+snippet = start ws prefix:prefix ws description:string separator body:body end {
+  return { prefix: prefix, description: description, body: body };
+}
+
+separator = [ ]* '\n'
+start = 'snippet'
+prefix = prefix:[A-Za-z0-9_]+ { return prefix.join(''); }
+body = body:bodyCharacter* { return body.join(''); }
+bodyCharacter = !end char:[a-z ] { return char; }
+end = '\nendsnippet'
+string
+  = ['] body:[^']* ['] { return body.join(''); }
+  / ["] body:[^"]* ["] { return body.join(''); }
+ws = [ \n]+