kotovalexarian-likes-github/jashkenas--coffeescript
1
0
Fork 0
mirror of https://github.com/jashkenas/coffeescript.git synced 2022-11-09 12:23:24 -05:00
Code Releases Activity

CoffeeScript 1.6.0

Browse source
This commit is contained in:
Jeremy Ashkenas 2013-03-05 08:19:08 +13:00
parent e417a0ca6f
commit 9f614fedec
73 changed files with 1236 additions and 718 deletions
Download patch file Download diff file Expand all files Collapse all files

155
documentation/docs/sourcemap.html Normal file
View file

@ -0,0 +1,155 @@
<!DOCTYPE html> <html> <head> <title>sourcemap.coffee</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <link rel="stylesheet" media="all" href="docco.css" /> </head> <body> <div id="container"> <div id="background"></div> <div id="jump_to"> Jump To &hellip; <div id="jump_wrapper"> <div id="jump_page"> <a class="source" href="browser.html"> browser.coffee </a> <a class="source" href="cake.html"> cake.coffee </a> <a class="source" href="coffee-script.html"> coffee-script.coffee </a> <a class="source" href="command.html"> command.coffee </a> <a class="source" href="grammar.html"> grammar.coffee </a> <a class="source" href="helpers.html"> helpers.coffee </a> <a class="source" href="index.html"> index.coffee </a> <a class="source" href="lexer.html"> lexer.coffee </a> <a class="source" href="nodes.html"> nodes.coffee </a> <a class="source" href="optparse.html"> optparse.coffee </a> <a class="source" href="repl.html"> repl.coffee </a> <a class="source" href="rewriter.html"> rewriter.coffee </a> <a class="source" href="sourcemap.html"> sourcemap.coffee </a> </div> </div> </div> <table cellpadding="0" cellspacing="0"> <thead> <tr> <th class="docs"> <h1> sourcemap.coffee </h1> </th> <th class="code"> </th> </tr> </thead> <tbody> <tr id="section-1"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-1">&#182;</a> </div> <h3>LineMapping</h3> </td> <td class="code"> <div class="highlight"><pre></pre></div> </td> </tr> <tr id="section-2"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-2">&#182;</a> </div> <p>Hold data about mappings for one line of generated source code.</p> </td> <td class="code"> <div class="highlight"><pre><span class="k">class</span> <span class="nx">LineMapping</span>
<span class="nv">constructor: </span><span class="nf">(@generatedLine) -&gt;</span></pre></div> </td> </tr> <tr id="section-3"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-3">&#182;</a> </div> <p>columnMap keeps track of which columns we've already mapped.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="vi">@columnMap = </span><span class="p">{}</span></pre></div> </td> </tr> <tr id="section-4"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-4">&#182;</a> </div> <p>columnMappings is an array of all column mappings, sorted by generated-column.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="vi">@columnMappings = </span><span class="p">[]</span>
<span class="nv">addMapping: </span><span class="nf">(generatedColumn, [sourceLine, sourceColumn], options={}) -&gt;</span>
<span class="k">if</span> <span class="nx">@columnMap</span><span class="p">[</span><span class="nx">generatedColumn</span><span class="p">]</span> <span class="o">and</span> <span class="nx">options</span><span class="p">.</span><span class="nx">noReplace</span></pre></div> </td> </tr> <tr id="section-5"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-5">&#182;</a> </div> <p>We already have a mapping for this column.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="k">return</span>
<span class="nx">@columnMap</span><span class="p">[</span><span class="nx">generatedColumn</span><span class="p">]</span> <span class="o">=</span> <span class="p">{</span>
<span class="nv">generatedLine: </span><span class="nx">@generatedLine</span>
<span class="nx">generatedColumn</span>
<span class="nx">sourceLine</span>
<span class="nx">sourceColumn</span>
<span class="p">}</span>
<span class="nx">@columnMappings</span><span class="p">.</span><span class="nx">push</span> <span class="nx">@columnMap</span><span class="p">[</span><span class="nx">generatedColumn</span><span class="p">]</span>
<span class="nx">@columnMappings</span><span class="p">.</span><span class="nx">sort</span> <span class="nf">(a,b) -&gt;</span> <span class="nx">a</span><span class="p">.</span><span class="nx">generatedColumn</span> <span class="o">-</span> <span class="nx">b</span><span class="p">.</span><span class="nx">generatedColumn</span>
<span class="nv">getSourcePosition: </span><span class="nf">(generatedColumn) -&gt;</span>
<span class="nv">answer = </span><span class="kc">null</span>
<span class="nv">lastColumnMapping = </span><span class="kc">null</span>
<span class="k">for</span> <span class="nx">columnMapping</span> <span class="k">in</span> <span class="nx">@columnMappings</span>
<span class="k">if</span> <span class="nx">columnMapping</span><span class="p">.</span><span class="nx">generatedColumn</span> <span class="o">&gt;</span> <span class="nx">generatedColumn</span>
<span class="k">break</span>
<span class="k">else</span>
<span class="nv">lastColumnMapping = </span><span class="nx">columnMapping</span>
<span class="k">if</span> <span class="nx">lastColumnMapping</span>
<span class="nv">answer = </span><span class="p">[</span><span class="nx">lastColumnMapping</span><span class="p">.</span><span class="nx">sourceLine</span><span class="p">,</span> <span class="nx">lastColumnMapping</span><span class="p">.</span><span class="nx">sourceColumn</span><span class="p">]</span></pre></div> </td> </tr> <tr id="section-6"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-6">&#182;</a> </div> <h3>SourceMap</h3> </td> <td class="code"> <div class="highlight"><pre></pre></div> </td> </tr> <tr id="section-7"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-7">&#182;</a> </div> <p>Maps locations in a generated source file back to locations in the original source file.</p>
<p>This is intentionally agnostic towards how a source map might be represented on disk. A
SourceMap can be converted to a "v3" style sourcemap with <code>#generateV3SourceMap()</code>, for example
but the SourceMap class itself knows nothing about v3 source maps.</p> </td> <td class="code"> <div class="highlight"><pre><span class="k">class</span> <span class="nx">exports</span><span class="p">.</span><span class="nx">SourceMap</span>
<span class="nv">constructor: </span><span class="p">()</span> <span class="nf">-&gt;</span></pre></div> </td> </tr> <tr id="section-8"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-8">&#182;</a> </div> <p><code>generatedLines</code> is an array of LineMappings, one per generated line.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="vi">@generatedLines = </span><span class="p">[]</span></pre></div> </td> </tr> <tr id="section-9"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-9">&#182;</a> </div> <p>Adds a mapping to this SourceMap.</p>
<p><code>sourceLocation</code> and <code>generatedLocation</code> are both [line, column] arrays.</p>
<p>If <code>options.noReplace</code> is true, then if there is already a mapping for
the specified <code>generatedLine</code> and <code>generatedColumn</code>, this will have no effect.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">addMapping: </span><span class="nf">(sourceLocation, generatedLocation, options={}) -&gt;</span>
<span class="p">[</span><span class="nx">generatedLine</span><span class="p">,</span> <span class="nx">generatedColumn</span><span class="p">]</span> <span class="o">=</span> <span class="nx">generatedLocation</span>
<span class="nv">lineMapping = </span><span class="nx">@generatedLines</span><span class="p">[</span><span class="nx">generatedLine</span><span class="p">]</span>
<span class="k">if</span> <span class="o">not</span> <span class="nx">lineMapping</span>
<span class="nv">lineMapping = </span><span class="nx">@generatedLines</span><span class="p">[</span><span class="nx">generatedLine</span><span class="p">]</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">LineMapping</span><span class="p">(</span><span class="nx">generatedLine</span><span class="p">)</span>
<span class="nx">lineMapping</span><span class="p">.</span><span class="nx">addMapping</span> <span class="nx">generatedColumn</span><span class="p">,</span> <span class="nx">sourceLocation</span><span class="p">,</span> <span class="nx">options</span></pre></div> </td> </tr> <tr id="section-10"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-10">&#182;</a> </div> <p>Returns [sourceLine, sourceColumn], or null if no mapping could be found.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">getSourcePosition: </span><span class="nf">([generatedLine, generatedColumn]) -&gt;</span>
<span class="nv">answer = </span><span class="kc">null</span>
<span class="nv">lineMapping = </span><span class="nx">@generatedLines</span><span class="p">[</span><span class="nx">generatedLine</span><span class="p">]</span>
<span class="k">if</span> <span class="o">not</span> <span class="nx">lineMapping</span></pre></div> </td> </tr> <tr id="section-11"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-11">&#182;</a> </div> <p>TODO: Search backwards for the line?</p> </td> <td class="code"> <div class="highlight"><pre> <span class="k">else</span>
<span class="nv">answer = </span><span class="nx">lineMapping</span><span class="p">.</span><span class="nx">getSourcePosition</span> <span class="nx">generatedColumn</span>
<span class="nx">answer</span></pre></div> </td> </tr> <tr id="section-12"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-12">&#182;</a> </div> <p><code>fn</code> will be called once for every recorded mapping, in the order in
which they occur in the generated source. <code>fn</code> will be passed an object
with four properties: sourceLine, sourceColumn, generatedLine, and
generatedColumn.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">forEachMapping: </span><span class="nf">(fn) -&gt;</span>
<span class="k">for</span> <span class="nx">lineMapping</span><span class="p">,</span> <span class="nx">generatedLineNumber</span> <span class="k">in</span> <span class="nx">@generatedLines</span>
<span class="k">if</span> <span class="nx">lineMapping</span>
<span class="k">for</span> <span class="nx">columnMapping</span> <span class="k">in</span> <span class="nx">lineMapping</span><span class="p">.</span><span class="nx">columnMappings</span>
<span class="nx">fn</span><span class="p">(</span><span class="nx">columnMapping</span><span class="p">)</span></pre></div> </td> </tr> <tr id="section-13"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-13">&#182;</a> </div> <h3>generateV3SourceMap</h3> </td> <td class="code"> <div class="highlight"><pre></pre></div> </td> </tr> <tr id="section-14"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-14">&#182;</a> </div> <p>Builds a V3 source map from a SourceMap object.
Returns the generated JSON as a string.</p> </td> <td class="code"> <div class="highlight"><pre><span class="nv">exports.generateV3SourceMap = </span><span class="nf">(sourceMap, sourceFile=null, generatedFile=null) -&gt;</span>
<span class="nv">writingGeneratedLine = </span><span class="mi">0</span>
<span class="nv">lastGeneratedColumnWritten = </span><span class="mi">0</span>
<span class="nv">lastSourceLineWritten = </span><span class="mi">0</span>
<span class="nv">lastSourceColumnWritten = </span><span class="mi">0</span>
<span class="nv">needComma = </span><span class="kc">no</span>
<span class="nv">mappings = </span><span class="s">&quot;&quot;</span>
<span class="nx">sourceMap</span><span class="p">.</span><span class="nx">forEachMapping</span> <span class="nf">(mapping) -&gt;</span>
<span class="k">while</span> <span class="nx">writingGeneratedLine</span> <span class="o">&lt;</span> <span class="nx">mapping</span><span class="p">.</span><span class="nx">generatedLine</span>
<span class="nv">lastGeneratedColumnWritten = </span><span class="mi">0</span>
<span class="nv">needComma = </span><span class="kc">no</span>
<span class="nx">mappings</span> <span class="o">+=</span> <span class="s">&quot;;&quot;</span>
<span class="nx">writingGeneratedLine</span><span class="o">++</span></pre></div> </td> </tr> <tr id="section-15"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-15">&#182;</a> </div> <p>Write a comma if we've already written a segment on this line.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="k">if</span> <span class="nx">needComma</span>
<span class="nx">mappings</span> <span class="o">+=</span> <span class="s">&quot;,&quot;</span>
<span class="nv">needComma = </span><span class="kc">no</span></pre></div> </td> </tr> <tr id="section-16"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-16">&#182;</a> </div> <p>Write the next segment.
Segments can be 1, 4, or 5 values. If just one, then it is a generated column which
doesn't match anything in the source code.</p>
<p>Fields are all zero-based, and relative to the previous occurence unless otherwise noted:
* starting-column in generated source, relative to previous occurence for the current line.
* index into the "sources" list
* starting line in the original source
* starting column in the original source
* index into the "names" list associated with this segment.</p> </td> <td class="code"> <div class="highlight"><pre></pre></div> </td> </tr> <tr id="section-17"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-17">&#182;</a> </div> <p>Add the generated start-column</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nx">mappings</span> <span class="o">+=</span> <span class="nx">exports</span><span class="p">.</span><span class="nx">vlqEncodeValue</span><span class="p">(</span><span class="nx">mapping</span><span class="p">.</span><span class="nx">generatedColumn</span> <span class="o">-</span> <span class="nx">lastGeneratedColumnWritten</span><span class="p">)</span>
<span class="nv">lastGeneratedColumnWritten = </span><span class="nx">mapping</span><span class="p">.</span><span class="nx">generatedColumn</span></pre></div> </td> </tr> <tr id="section-18"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-18">&#182;</a> </div> <p>Add the index into the sources list</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nx">mappings</span> <span class="o">+=</span> <span class="nx">exports</span><span class="p">.</span><span class="nx">vlqEncodeValue</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span></pre></div> </td> </tr> <tr id="section-19"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-19">&#182;</a> </div> <p>Add the source start-line</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nx">mappings</span> <span class="o">+=</span> <span class="nx">exports</span><span class="p">.</span><span class="nx">vlqEncodeValue</span><span class="p">(</span><span class="nx">mapping</span><span class="p">.</span><span class="nx">sourceLine</span> <span class="o">-</span> <span class="nx">lastSourceLineWritten</span><span class="p">)</span>
<span class="nv">lastSourceLineWritten = </span><span class="nx">mapping</span><span class="p">.</span><span class="nx">sourceLine</span></pre></div> </td> </tr> <tr id="section-20"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-20">&#182;</a> </div> <p>Add the source start-column</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nx">mappings</span> <span class="o">+=</span> <span class="nx">exports</span><span class="p">.</span><span class="nx">vlqEncodeValue</span><span class="p">(</span><span class="nx">mapping</span><span class="p">.</span><span class="nx">sourceColumn</span> <span class="o">-</span> <span class="nx">lastSourceColumnWritten</span><span class="p">)</span>
<span class="nv">lastSourceColumnWritten = </span><span class="nx">mapping</span><span class="p">.</span><span class="nx">sourceColumn</span></pre></div> </td> </tr> <tr id="section-21"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-21">&#182;</a> </div> <p>TODO: Do we care about symbol names for CoffeeScript? Probably not.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">needComma = </span><span class="kc">yes</span>
<span class="nv">answer = </span><span class="p">{</span>
<span class="nv">version: </span><span class="mi">3</span>
<span class="nv">file: </span><span class="nx">generatedFile</span>
<span class="nv">sourceRoot: </span><span class="s">&quot;&quot;</span>
<span class="nv">sources: </span><span class="k">if</span> <span class="nx">sourceFile</span> <span class="k">then</span> <span class="p">[</span><span class="nx">sourceFile</span><span class="p">]</span> <span class="k">else</span> <span class="p">[]</span>
<span class="nv">names: </span><span class="p">[]</span>
<span class="nx">mappings</span>
<span class="p">}</span>
<span class="k">return</span> <span class="nx">JSON</span><span class="p">.</span><span class="nx">stringify</span> <span class="nx">answer</span><span class="p">,</span> <span class="kc">null</span><span class="p">,</span> <span class="mi">2</span></pre></div> </td> </tr> <tr id="section-22"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-22">&#182;</a> </div> <p>Load a SourceMap from a JSON string. Returns the SourceMap object.</p> </td> <td class="code"> <div class="highlight"><pre><span class="nv">exports.loadV3SourceMap = </span><span class="nf">(sourceMap) -&gt;</span>
<span class="nx">todo</span><span class="p">()</span></pre></div> </td> </tr> <tr id="section-23"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-23">&#182;</a> </div> <h3>Base64 encoding helpers</h3> </td> <td class="code"> <div class="highlight"><pre><span class="nv">BASE64_CHARS = </span><span class="s">&#39;ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/&#39;</span>
<span class="nv">MAX_BASE64_VALUE = </span><span class="nx">BASE64_CHARS</span><span class="p">.</span><span class="nx">length</span> <span class="o">-</span> <span class="mi">1</span>
<span class="nv">encodeBase64Char = </span><span class="nf">(value) -&gt;</span>
<span class="k">if</span> <span class="nx">value</span> <span class="o">&gt;</span> <span class="nx">MAX_BASE64_VALUE</span>
<span class="k">throw</span> <span class="k">new</span> <span class="nb">Error</span> <span class="s">&quot;Cannot encode value </span><span class="si">#{</span><span class="nx">value</span><span class="si">}</span><span class="s"> &gt; </span><span class="si">#{</span><span class="nx">MAX_BASE64_VALUE</span><span class="si">}</span><span class="s">&quot;</span>
<span class="k">else</span> <span class="k">if</span> <span class="nx">value</span> <span class="o">&lt;</span> <span class="mi">0</span>
<span class="k">throw</span> <span class="k">new</span> <span class="nb">Error</span> <span class="s">&quot;Cannot encode value </span><span class="si">#{</span><span class="nx">value</span><span class="si">}</span><span class="s"> &lt; 0&quot;</span>
<span class="nx">BASE64_CHARS</span><span class="p">[</span><span class="nx">value</span><span class="p">]</span>
<span class="nv">decodeBase64Char = </span><span class="nf">(char) -&gt;</span>
<span class="nv">value = </span><span class="nx">BASE64_CHARS</span><span class="p">.</span><span class="nx">indexOf</span> <span class="nx">char</span>
<span class="k">if</span> <span class="nx">value</span> <span class="o">==</span> <span class="o">-</span><span class="mi">1</span>
<span class="k">throw</span> <span class="k">new</span> <span class="nb">Error</span> <span class="s">&quot;Invalid Base 64 character: </span><span class="si">#{</span><span class="nx">char</span><span class="si">}</span><span class="s">&quot;</span>
<span class="nx">value</span></pre></div> </td> </tr> <tr id="section-24"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-24">&#182;</a> </div> <h3>Base 64 VLQ encoding/decoding helpers</h3> </td> <td class="code"> <div class="highlight"><pre></pre></div> </td> </tr> <tr id="section-25"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-25">&#182;</a> </div> <p>Note that SourceMap VLQ encoding is "backwards". MIDI style VLQ encoding puts the
most-significant-bit (MSB) from the original value into the MSB of the VLQ encoded value
(see http://en.wikipedia.org/wiki/File:Uintvar_coding.svg). SourceMap VLQ does things
the other way around, with the least significat four bits of the original value encoded
into the first byte of the VLQ encoded value.</p> </td> <td class="code"> <div class="highlight"><pre><span class="nv">VLQ_SHIFT = </span><span class="mi">5</span>
<span class="nv">VLQ_CONTINUATION_BIT = </span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="nx">VLQ_SHIFT</span> <span class="c1"># 0010 0000</span>
<span class="nv">VLQ_VALUE_MASK = </span><span class="nx">VLQ_CONTINUATION_BIT</span> <span class="o">-</span> <span class="mi">1</span> <span class="c1"># 0001 1111</span></pre></div> </td> </tr> <tr id="section-26"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-26">&#182;</a> </div> <p>Encode a value as Base 64 VLQ.</p> </td> <td class="code"> <div class="highlight"><pre><span class="nv">exports.vlqEncodeValue = </span><span class="nf">(value) -&gt;</span></pre></div> </td> </tr> <tr id="section-27"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-27">&#182;</a> </div> <p>Least significant bit represents the sign.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">signBit = </span><span class="k">if</span> <span class="nx">value</span> <span class="o">&lt;</span> <span class="mi">0</span> <span class="k">then</span> <span class="mi">1</span> <span class="k">else</span> <span class="mi">0</span></pre></div> </td> </tr> <tr id="section-28"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-28">&#182;</a> </div> <p>Next bits are the actual value</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">valueToEncode = </span><span class="p">(</span><span class="nb">Math</span><span class="p">.</span><span class="nx">abs</span><span class="p">(</span><span class="nx">value</span><span class="p">)</span> <span class="o">&lt;&lt;</span> <span class="mi">1</span><span class="p">)</span> <span class="o">+</span> <span class="nx">signBit</span>
<span class="nv">answer = </span><span class="s">&quot;&quot;</span></pre></div> </td> </tr> <tr id="section-29"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-29">&#182;</a> </div> <p>Make sure we encode at least one character, even if valueToEncode is 0.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="k">while</span> <span class="nx">valueToEncode</span> <span class="o">||</span> <span class="o">!</span><span class="nx">answer</span>
<span class="nv">nextVlqChunk = </span><span class="nx">valueToEncode</span> <span class="o">&amp;</span> <span class="nx">VLQ_VALUE_MASK</span>
<span class="nv">valueToEncode = </span><span class="nx">valueToEncode</span> <span class="o">&gt;&gt;</span> <span class="nx">VLQ_SHIFT</span>
<span class="k">if</span> <span class="nx">valueToEncode</span>
<span class="nx">nextVlqChunk</span> <span class="o">|=</span> <span class="nx">VLQ_CONTINUATION_BIT</span>
<span class="nx">answer</span> <span class="o">+=</span> <span class="nx">encodeBase64Char</span><span class="p">(</span><span class="nx">nextVlqChunk</span><span class="p">)</span>
<span class="k">return</span> <span class="nx">answer</span></pre></div> </td> </tr> <tr id="section-30"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-30">&#182;</a> </div> <p>Decode a Base 64 VLQ value.</p>
<p>Returns <code>[value, consumed]</code> where <code>value</code> is the decoded value, and <code>consumed</code> is the number
of characters consumed from <code>str</code>.</p> </td> <td class="code"> <div class="highlight"><pre><span class="nv">exports.vlqDecodeValue = </span><span class="nf">(str, offset=0) -&gt;</span>
<span class="nv">position = </span><span class="nx">offset</span>
<span class="nv">done = </span><span class="kc">false</span>
<span class="nv">value = </span><span class="mi">0</span>
<span class="nv">continuationShift = </span><span class="mi">0</span>
<span class="k">while</span> <span class="o">!</span><span class="nx">done</span>
<span class="nv">nextVlqChunk = </span><span class="nx">decodeBase64Char</span><span class="p">(</span><span class="nx">str</span><span class="p">[</span><span class="nx">position</span><span class="p">])</span>
<span class="nx">position</span> <span class="o">+=</span> <span class="mi">1</span>
<span class="nv">nextChunkValue = </span><span class="nx">nextVlqChunk</span> <span class="o">&amp;</span> <span class="nx">VLQ_VALUE_MASK</span>
<span class="nx">value</span> <span class="o">+=</span> <span class="p">(</span><span class="nx">nextChunkValue</span> <span class="o">&lt;&lt;</span> <span class="nx">continuationShift</span><span class="p">)</span>
<span class="k">if</span> <span class="o">!</span><span class="p">(</span><span class="nx">nextVlqChunk</span> <span class="o">&amp;</span> <span class="nx">VLQ_CONTINUATION_BIT</span><span class="p">)</span></pre></div> </td> </tr> <tr id="section-31"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-31">&#182;</a> </div> <p>We'll be done after this character.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">done = </span><span class="kc">true</span></pre></div> </td> </tr> <tr id="section-32"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-32">&#182;</a> </div> <p>Bits are encoded least-significant first (opposite of MIDI VLQ). Increase the
continuationShift, so the next byte will end up where it should in the value.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nx">continuationShift</span> <span class="o">+=</span> <span class="nx">VLQ_SHIFT</span>
<span class="nv">consumed = </span><span class="nx">position</span> <span class="o">-</span> <span class="nx">offset</span></pre></div> </td> </tr> <tr id="section-33"> <td class="docs"> <div class="pilwrap"> <a class="pilcrow" href="#section-33">&#182;</a> </div> <p>Least significant bit represents the sign.</p> </td> <td class="code"> <div class="highlight"><pre> <span class="nv">signBit = </span><span class="nx">value</span> <span class="o">&amp;</span> <span class="mi">1</span>
<span class="nv">value = </span><span class="nx">value</span> <span class="o">&gt;&gt;</span> <span class="mi">1</span>
<span class="k">if</span> <span class="nx">signBit</span> <span class="k">then</span> <span class="nv">value = </span><span class="o">-</span><span class="nx">value</span>
<span class="k">return</span> <span class="p">[</span><span class="nx">value</span><span class="p">,</span> <span class="nx">consumed</span><span class="p">]</span>
</pre></div> </td> </tr> </tbody> </table> </div> </body> </html>