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112 lines
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<title>Lazy Strings In Guile - Debugging with GDB</title>
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<div class="node">
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<a name="Lazy-Strings-In-Guile"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Architectures-In-Guile.html#Architectures-In-Guile">Architectures In Guile</a>,
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Previous: <a rel="previous" accesskey="p" href="Breakpoints-In-Guile.html#Breakpoints-In-Guile">Breakpoints In Guile</a>,
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Up: <a rel="up" accesskey="u" href="Guile-API.html#Guile-API">Guile API</a>
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<h5 class="subsubsection">23.3.3.20 Guile representation of lazy strings.</h5>
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<p><a name="index-lazy-strings-in-guile-2804"></a><a name="index-g_t_003cgdb_003alazy_002dstring_003e-2805"></a>
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A <dfn>lazy string</dfn> is a string whose contents is not retrieved or
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encoded until it is needed.
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<p>A <code><gdb:lazy-string></code> is represented in <span class="sc">gdb</span> as an
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<code>address</code> that points to a region of memory, an <code>encoding</code>
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that will be used to encode that region of memory, and a <code>length</code>
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to delimit the region of memory that represents the string. The
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difference between a <code><gdb:lazy-string></code> and a string wrapped within
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a <code><gdb:value></code> is that a <code><gdb:lazy-string></code> will be treated
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differently by <span class="sc">gdb</span> when printing. A <code><gdb:lazy-string></code> is
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retrieved and encoded during printing, while a <code><gdb:value></code>
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wrapping a string is immediately retrieved and encoded on creation.
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<p>The following lazy-string-related procedures are provided by the
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<code>(gdb)</code> module:
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<div class="defun">
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— Scheme Procedure: <b>lazy-string?</b><var> object<a name="index-lazy_002dstring_003f-2806"></a></var><br>
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<blockquote><p>Return <code>#t</code> if <var>object</var> is an object of type <code><gdb:lazy-string></code>.
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Otherwise return <code>#f</code>.
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</p></blockquote></div>
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<div class="defun">
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— Scheme Procedure: <b>lazy-string-address</b><var> lazy-sring<a name="index-lazy_002dstring_002daddress-2807"></a></var><br>
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<blockquote><p>Return the address of <var>lazy-string</var>.
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</p></blockquote></div>
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<div class="defun">
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— Scheme Procedure: <b>lazy-string-length</b><var> lazy-string<a name="index-lazy_002dstring_002dlength-2808"></a></var><br>
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<blockquote><p>Return the length of <var>lazy-string</var> in characters. If the
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length is -1, then the string will be fetched and encoded up to the
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first null of appropriate width.
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</p></blockquote></div>
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<div class="defun">
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— Scheme Procedure: <b>lazy-string-encoding</b><var> lazy-string<a name="index-lazy_002dstring_002dencoding-2809"></a></var><br>
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<blockquote><p>Return the encoding that will be applied to <var>lazy-string</var>
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when the string is printed by <span class="sc">gdb</span>. If the encoding is not
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set, or contains an empty string, then <span class="sc">gdb</span> will select the
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most appropriate encoding when the string is printed.
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</p></blockquote></div>
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<div class="defun">
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— Scheme Procedure: <b>lazy-string-type</b><var> lazy-string<a name="index-lazy_002dstring_002dtype-2810"></a></var><br>
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<blockquote><p>Return the type that is represented by <var>lazy-string</var>'s type.
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For a lazy string this is a pointer or array type. To
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resolve this to the lazy string's character type, use <code>type-target-type</code>.
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See <a href="Types-In-Guile.html#Types-In-Guile">Types In Guile</a>.
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</p></blockquote></div>
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<div class="defun">
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— Scheme Procedure: <b>lazy-string->value</b><var> lazy-string<a name="index-lazy_002dstring_002d_003evalue-2811"></a></var><br>
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<blockquote><p>Convert the <code><gdb:lazy-string></code> to a <code><gdb:value></code>. This value
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will point to the string in memory, but will lose all the delayed
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retrieval, encoding and handling that <span class="sc">gdb</span> applies to a
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<code><gdb:lazy-string></code>.
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</p></blockquote></div>
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