149 lines
6.5 KiB
HTML
149 lines
6.5 KiB
HTML
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<?xml version="1.0" encoding="utf-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml"><head>
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<title>.</title>
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<style type="text/css">
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* { color: #000; background: #fff; max-width: 700px; }
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tt, pre { background: #dedede; color: #111; font-family: monospace;
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white-space: pre; display: block; width: 100%; }
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.indentedcode { margin-left: 2em; margin-right: 2em; }
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.codeblock {
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background: #dedede; color: #111; font-family: monospace;
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box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
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padding: 7px;
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display: block;
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}
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.indentedlist { margin-left: 2em; color: #000; }
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span { white-space: pre; }
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.text { color: #000; white-space: pre; background: #dedede; }
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.colon { color: #000; background: #dedede; }
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.note { color: #000; background: #dedede; }
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.str { color: #000; text-decoration: underline; background: #dedede; }
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.num { color: #000; background: #dedede; font-weight: bold; font-style: italic; }
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.fnum { color: #000; font-weight: bold; background: #dedede; }
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.ptr { color: #000; font-weight: bold; background: #dedede; }
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.fetch { color: #000; font-style: italic; background: #dedede; }
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.store { color: #000; font-style: italic; background: #dedede; }
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.char { color: #000; background: #dedede; }
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.inst { color: #000; background: #dedede; }
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.defer { color: #000; background: #dedede; }
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.imm { color: #000; font-weight: bold; background: #dedede; }
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.prim { color: #000; font-weight: bolder; background: #dedede; }
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.tt { white-space: pre; font-family: monospace; background: #dedede; }
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.h1, .h2, .h3, .h4 { white-space: normal; }
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.h1 { font-size: 125%; }
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.h2 { font-size: 120%; }
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.h3 { font-size: 115%; }
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.h4 { font-size: 110%; }
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.hr { display: block; height: 2px; background: #000000; }
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</style>
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</head><body>
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<p><span class="h1">Working With The Dictionary</span>
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<br/><br/>
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The Dictionary is a linked list containing the dictionary
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headers.
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<br/><br/>
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<span class="h2">Namespace</span>
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<br/><br/>
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Words operating on the dictionary are in the <span class="tt">d:</span> namespace.
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<br/><br/>
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<span class="h2">Variables</span>
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<br/><br/>
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<span class="tt">Dictionary</span> is a variable holding a pointer to the most recent
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header.
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<br/><br/>
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<span class="h2">Header Structure</span>
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<br/><br/>
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Each entry follows the following structure:
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<br/><br/>
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<tt class='indentedcode'>Offset Contains</tt>
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<tt class='indentedcode'>------ ---------------------------</tt>
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<tt class='indentedcode'>0000 Link to Prior Header</tt>
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<tt class='indentedcode'>0001 Link to XT</tt>
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<tt class='indentedcode'>0002 Link to Class Handler</tt>
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<tt class='indentedcode'>0003+ Word name (null terminated)</tt>
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<br/><br/>
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RETRO provides words for accessing the fields in a portable
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manner. It's recommended to use these to allow for future
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revision of the header structure.
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<br/><br/>
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<span class="h2">Accessing Fields</span>
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<br/><br/>
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Given a pointer to a header, you can use <span class="tt">d:xt</span>, <span class="tt">d:class</span>,
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and <span class="tt">d:name</span> to access the address of each specific field.
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There is no <span class="tt">d:link</span>, as the link will always be the first
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field.
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<br/><br/>
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<span class="h2">Shortcuts For The Latest Header</span>
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<br/><br/>
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RETRO provides several words for operating on the most recent
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header.
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<br/><br/>
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<span class="tt">d:last</span> returns a pointer to the latest header. <span class="tt">d:last.xt</span>
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will give the contents of the <span class="tt">d:xt</span> field for the latest
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header. There are also <span class="tt">d:last.class</span> and <span class="tt">d:last.name</span>.
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<br/><br/>
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<span class="h2">Adding Headers</span>
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<br/><br/>
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Two words exist for making new headers. The easy one is
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<span class="tt">d:create</span>. This takes a string for the name and makes a
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new header with the class set to <span class="tt">class:data</span> and the XT
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field pointing to <span class="tt">here</span>.
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<br/><br/>
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Example:
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<br/><br/>
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<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='str'>'Base</span> d:create </span><br/>
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<span class="tt">```</span></span><br/><br/>
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The other is <span class="tt">d:add-header</span>. This takes a string, a pointer
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to the class handler, and a pointer for the XT field and
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builds a new header using these.
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<br/><br/>
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Example:
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<br/><br/>
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<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='str'>'Base</span> <span class='ptr'>&class:data</span> <span class='num'>#10000</span> d:add-header </span><br/>
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<span class="tt">```</span></span><br/><br/>
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<span class="h2">Searching</span>
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<br/><br/>
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RETRO provides two words for searching the dictionary.
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<br/><br/>
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<span class="tt">d:lookup</span> takes a string and tries to find it in the
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dictionary. It will return a pointer to the dictionary header
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or a value of zero if the word was not found.
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<br/><br/>
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<span class="tt">d:lookup-xt</span> takes a pointer and will return the dictionary
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header that has this as the <span class="tt">d:xt</span> field, or zero if no match
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is found.
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<br/><br/>
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<span class="h2">Iteration</span>
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<br/><br/>
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You can use the <span class="tt">d:for-each</span> combinator to iterate over all
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entries in the dictionary. For instance, to display the names
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of all words:
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<br/><br/>
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<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='imm'>[</span> d:name s:put sp <span class='imm'>]</span> d:for-each </span><br/>
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<span class="tt">```</span></span><br/><br/>
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For each entry, this combinator will push a pointer to the
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entry to the stack and call the quotation.
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<br/><br/>
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<span class="h2">Listing Words</span>
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<br/><br/>
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Most Forth systems provide WORDS for listing the names of all
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words in the dictionary. RETRO does as well, but this is named
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<span class="tt">d:words</span>.
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<br/><br/>
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This isn't super useful as looking through several hundred
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names is annoying. RETRO also provides <span class="tt">d:words-with</span> to help
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in filtering the results.
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<br/><br/>
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Example:
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<br/><br/>
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<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='str'>'class:</span> d:words-with </span><br/>
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<span class="tt">```</span></span><br/><br/>
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</p>
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</body></html>
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