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diff --git a/doc/groff.html.node/Input-Line-Traps.html b/doc/groff.html.node/Input-Line-Traps.html new file mode 100644 index 0000000..f0d7fef --- /dev/null +++ b/doc/groff.html.node/Input-Line-Traps.html @@ -0,0 +1,185 @@ +<!DOCTYPE html> +<html> +<!-- Created by GNU Texinfo 7.0.3, https://www.gnu.org/software/texinfo/ --> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> +<!-- This manual documents GNU troff version 1.23.0. + +Copyright © 1994-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with no +Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A +copy of the license is included in the section entitled "GNU Free +Documentation License". --> +<title>Input Line Traps (The GNU Troff Manual)</title> + +<meta name="description" content="Input Line Traps (The GNU Troff Manual)"> +<meta name="keywords" content="Input Line Traps (The GNU Troff Manual)"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta name="viewport" content="width=device-width,initial-scale=1"> + +<link href="index.html" rel="start" title="Top"> +<link href="Request-Index.html" rel="index" title="Request Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Traps.html" rel="up" title="Traps"> +<link href="Blank-Line-Traps.html" rel="next" title="Blank Line Traps"> +<link href="Diversion-Traps.html" rel="prev" title="Diversion Traps"> +<style type="text/css"> +<!-- +a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em} +div.example {margin-left: 3.2em} +span.r {font-family: initial; font-weight: normal; font-style: normal} +span:hover a.copiable-link {visibility: visible} +strong.def-name {font-family: monospace; font-weight: bold; font-size: larger} +--> +</style> + + +</head> + +<body lang="en"> +<div class="subsection-level-extent" id="Input-Line-Traps"> +<div class="nav-panel"> +<p> +Next: <a href="Blank-Line-Traps.html" accesskey="n" rel="next">Blank Line Traps</a>, Previous: <a href="Diversion-Traps.html" accesskey="p" rel="prev">Diversion Traps</a>, Up: <a href="Traps.html" accesskey="u" rel="up">Traps</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Request-Index.html" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<h4 class="subsection" id="Input-Line-Traps-1">5.28.2 Input Line Traps</h4> +<a class="index-entry-id" id="index-input-line-traps"></a> +<a class="index-entry-id" id="index-traps_002c-input-line"></a> + +<dl class="first-deffn"> +<dt class="deffn" id="index-_002eit"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.it</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span> <span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eit'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-it"></a> +</dd><dt class="deffnx def-cmd-deffn" id="index-_002eitc"><span class="category-def">Request: </span><span><strong class="def-name"><code class="t">.itc</code></strong> <var class="def-var-arguments">[<span class="r"><i class="slanted">n</i></span> <span class="r"><i class="slanted">name</i></span>]</var><a class="copiable-link" href='#index-_002eitc'> ¶</a></span></dt> +<dd><a class="index-entry-id" id="index-itc"></a> +<a class="index-entry-id" id="index-setting-input-line-trap-_0028it_002c-itc_0029"></a> +<a class="index-entry-id" id="index-input-line-trap_002c-setting-_0028it_002c-itc_0029"></a> +<a class="index-entry-id" id="index-trap_002c-input-line_002c-setting-_0028it_002c-itc_0029"></a> +<a class="index-entry-id" id="index-clearing-input-line-trap-_0028it_002c-itc_0029"></a> +<a class="index-entry-id" id="index-input-line-trap_002c-clearing-_0028it_002c-itc_0029"></a> +<a class="index-entry-id" id="index-trap_002c-input-line_002c-clearing-_0028it_002c-itc_0029"></a> +<p>Set an input line trap, calling macro <var class="var">name</var> after processing the +next <var class="var">n</var> productive input lines (recall <a class="ref" href="Manipulating-Filling-and-Adjustment.html">Manipulating Filling and Adjustment</a>). Any existing input line trap in the +environment is replaced. Without arguments, <code class="code">it</code> and <code class="code">itc</code> +clear any input line trap that has not yet sprung. +</p> +<p>Consider a macro ‘<samp class="samp">.ST <var class="var">s n</var></samp>’ which sets the next +<var class="var">n</var> input lines in the font style <var class="var">s</var>. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de ST \" Use style $1 for next $2 text lines. +. it \\$2 ES +. ft \\$1 +.. +.de ES \" end ST +. ft R +.. +.ST I 1 +oblique +face +.ST I 1 +oblique\c +face + ⇒ <i class="i">oblique</i> face <i class="i">oblique</i>face <span class="r">(second “face” upright)</span> +</pre></div></div> + +<a class="index-entry-id" id="index-input-line-traps-and-interrupted-lines-_0028itc_0029"></a> +<a class="index-entry-id" id="index-interrupted-lines-and-input-line-traps-_0028itc_0029"></a> +<a class="index-entry-id" id="index-traps_002c-input-line_002c-and-interrupted-lines-_0028itc_0029"></a> +<a class="index-entry-id" id="index-lines_002c-interrupted_002c-and-input-line-traps-_0028itc_0029"></a> +<p>Unlike the <code class="code">ce</code> and <code class="code">rj</code> requests, <code class="code">it</code> counts lines +interrupted with the <code class="code">\c</code> escape sequence separately (see <a class="pxref" href="Line-Continuation.html">Line Continuation</a>); <code class="code">itc</code> does not. To see the difference, let’s +change the previous example to use <code class="code">itc</code> instead. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted"><span class="r">…</span> +. itc \\$2 ES +<span class="r">…</span> + ⇒ <i class="i">oblique</i> face <i class="i">obliqueface</i> <span class="r">(second “face” oblique)</span> +</pre></div></div> + +<p>You can think of the <code class="code">ce</code> and <code class="code">rj</code> requests as implicitly +creating an input line trap with <code class="code">itc</code> that schedules a break when +the trap is sprung. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de BR +. br +. <i class="slanted">internal: disable centering-without-filling</i> +.. +. +.de ce +. if \\n[.br] .br +. itc \\$1 BR +. <i class="slanted">internal: enable centering-without-filling</i> +.. +</pre></div></div> + +<p>Let us consider in more detail the sorts of input lines that are or are +not “productive”. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">.de Trap +TRAP SPRUNG +.. +.de Mac +.if r a \l'5n' +.. +.it 2 Trap +. +foo +.Mac +bar +baz +.it 1 Trap +.sp \" moves, but does not write or draw +qux +.itc 1 Trap +\h'5n'\c \" moves, but does not write or draw +jat +</pre></div></div> + +<p>When ‘<samp class="samp">Trap</samp>’ gets called depends on whether the ‘<samp class="samp">a</samp>’ register is +defined; the control line with the <code class="code">if</code> request may or may not +produce written output. We also see that the spacing request <code class="code">sp</code>, +while certainly affecting the output, does not spring the input line +trap. Similarly, the horizontal motion escape sequence <code class="code">\h</code> also +affected the output, but was not “written”. Observe that we had to +follow it with <code class="code">\c</code> and use <code class="code">itc</code> to prevent the newline at +the end of the text line from causing a word break, which, like an +ordinary space character, counts as written output. +</p> +<div class="example"> +<div class="group"><pre class="example-preformatted">$ groff -Tascii input-trap-example.groff + ⇒ foo bar TRAP SPRUNG baz + ⇒ + ⇒ qux TRAP SPRUNG jat TRAP SPRUNG +$ groff -Tascii -ra1 input-trap-example.groff + ⇒ foo _____ TRAP SPRUNG bar baz + ⇒ + ⇒ qux TRAP SPRUNG jat TRAP SPRUNG +</pre></div></div> +</dd></dl> + +<p>Input line traps are associated with the environment +(see <a class="pxref" href="Environments.html">Environments</a>); switching to another environment suspends the +current input line trap, and going back resumes it, restoring the count +of qualifying lines enumerated in that environment. +</p> + +</div> +<hr> +<div class="nav-panel"> +<p> +Next: <a href="Blank-Line-Traps.html">Blank Line Traps</a>, Previous: <a href="Diversion-Traps.html">Diversion Traps</a>, Up: <a href="Traps.html">Traps</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Request-Index.html" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |