/usr/share/doc/bison-doc/html/Java-Differences.html is in bison-doc 1:3.0.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!--
This manual (22 January 2015) is for GNU Bison (version
3.0.4), the GNU parser generator.
Copyright (C) 1988-1993, 1995, 1998-2015 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, with the Front-Cover texts
being "A GNU Manual," and with the Back-Cover Texts as in
(a) below. A copy of the license is included in the section entitled
"GNU Free Documentation License."
(a) The FSF's Back-Cover Text is: "You have the freedom to copy and
modify this GNU manual. Buying copies from the FSF
supports it in developing GNU and promoting software
freedom." -->
<!-- Created by GNU Texinfo 6.0, http://www.gnu.org/software/texinfo/ -->
<head>
<title>Bison 3.0.4: Java Differences</title>
<meta name="description" content="Bison 3.0.4: Java Differences">
<meta name="keywords" content="Bison 3.0.4: Java Differences">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="Index-of-Terms.html#Index-of-Terms" rel="index" title="Index of Terms">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Java-Parsers.html#Java-Parsers" rel="up" title="Java Parsers">
<link href="Java-Declarations-Summary.html#Java-Declarations-Summary" rel="next" title="Java Declarations Summary">
<link href="Java-Push-Parser-Interface.html#Java-Push-Parser-Interface" rel="prev" title="Java Push Parser Interface">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smalllisp {margin-left: 3.2em}
kbd {font-style: oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space: nowrap}
span.nolinebreak {white-space: nowrap}
span.roman {font-family: serif; font-weight: normal}
span.sansserif {font-family: sans-serif; font-weight: normal}
ul.no-bullet {list-style: none}
-->
</style>
</head>
<body lang="en">
<a name="Java-Differences"></a>
<div class="header">
<p>
Next: <a href="Java-Declarations-Summary.html#Java-Declarations-Summary" accesskey="n" rel="next">Java Declarations Summary</a>, Previous: <a href="Java-Push-Parser-Interface.html#Java-Push-Parser-Interface" accesskey="p" rel="prev">Java Push Parser Interface</a>, Up: <a href="Java-Parsers.html#Java-Parsers" accesskey="u" rel="up">Java Parsers</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Terms.html#Index-of-Terms" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Differences-between-C_002fC_002b_002b-and-Java-Grammars"></a>
<h4 class="subsection">10.2.8 Differences between C/C++ and Java Grammars</h4>
<p>The different structure of the Java language forces several differences
between C/C++ grammars, and grammars designed for Java parsers. This
section summarizes these differences.
</p>
<ul>
<li> Java lacks a preprocessor, so the <code>YYERROR</code>, <code>YYACCEPT</code>,
<code>YYABORT</code> symbols (see <a href="Table-of-Symbols.html#Table-of-Symbols">Table of Symbols</a>) cannot obviously be
macros. Instead, they should be preceded by <code>return</code> when they
appear in an action. The actual definition of these symbols is
opaque to the Bison grammar, and it might change in the future. The
only meaningful operation that you can do, is to return them.
See <a href="Java-Action-Features.html#Java-Action-Features">Java Action Features</a>.
<p>Note that of these three symbols, only <code>YYACCEPT</code> and
<code>YYABORT</code> will cause a return from the <code>yyparse</code>
method<a name="DOCF1" href="#FOOT1"><sup>1</sup></a>.
</p>
</li><li> Java lacks unions, so <code>%union</code> has no effect. Instead, semantic
values have a common base type: <code>Object</code> or as specified by
‘<samp>%define api.value.type</samp>’. Angle brackets on <code>%token</code>, <code>type</code>,
<code>$<var>n</var></code> and <code>$$</code> specify subtypes rather than fields of
an union. The type of <code>$$</code>, even with angle brackets, is the base
type since Java casts are not allow on the left-hand side of assignments.
Also, <code>$<var>n</var></code> and <code>@<var>n</var></code> are not allowed on the
left-hand side of assignments. See <a href="Java-Semantic-Values.html#Java-Semantic-Values">Java Semantic Values</a>, and
<a href="Java-Action-Features.html#Java-Action-Features">Java Action Features</a>.
</li><li> The prologue declarations have a different meaning than in C/C++ code.
<dl compact="compact">
<dt><code>%code imports</code></dt>
<dd><p>blocks are placed at the beginning of the Java source code. They may
include copyright notices. For a <code>package</code> declarations, it is
suggested to use ‘<samp>%define package</samp>’ instead.
</p>
</dd>
<dt>unqualified <code>%code</code></dt>
<dd><p>blocks are placed inside the parser class.
</p>
</dd>
<dt><code>%code lexer</code></dt>
<dd><p>blocks, if specified, should include the implementation of the
scanner. If there is no such block, the scanner can be any class
that implements the appropriate interface (see <a href="Java-Scanner-Interface.html#Java-Scanner-Interface">Java Scanner Interface</a>).
</p></dd>
</dl>
<p>Other <code>%code</code> blocks are not supported in Java parsers.
In particular, <code>%{ … %}</code> blocks should not be used
and may give an error in future versions of Bison.
</p>
<p>The epilogue has the same meaning as in C/C++ code and it can
be used to define other classes used by the parser <em>outside</em>
the parser class.
</p></li></ul>
<div class="footnote">
<hr>
<h4 class="footnotes-heading">Footnotes</h4>
<h3><a name="FOOT1" href="#DOCF1">(1)</a></h3>
<p>Java parsers include the actions in a separate
method than <code>yyparse</code> in order to have an intuitive syntax that
corresponds to these C macros.</p>
</div>
<hr>
<div class="header">
<p>
Next: <a href="Java-Declarations-Summary.html#Java-Declarations-Summary" accesskey="n" rel="next">Java Declarations Summary</a>, Previous: <a href="Java-Push-Parser-Interface.html#Java-Push-Parser-Interface" accesskey="p" rel="prev">Java Push Parser Interface</a>, Up: <a href="Java-Parsers.html#Java-Parsers" accesskey="u" rel="up">Java Parsers</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Terms.html#Index-of-Terms" title="Index" rel="index">Index</a>]</p>
</div>
</body>
</html>
|