mirror of
https://github.com/fmtlib/fmt.git
synced 2025-07-30 18:57:34 +02:00
Update paper
This commit is contained in:
Victor Zverovich
@ -4,6 +4,48 @@
|
|||||||
<head>
|
<head>
|
||||||
<meta http-equiv="Content-Type" content="text/html;charset=US-ASCII">
|
<meta http-equiv="Content-Type" content="text/html;charset=US-ASCII">
|
||||||
<title>Text Formatting</title>
|
<title>Text Formatting</title>
|
||||||
|
|
||||||
|
<style type="text/css">
|
||||||
|
|
||||||
|
body { color: #000000; background-color: #FFFFFF; }
|
||||||
|
del { text-decoration: line-through; color: #8B0040; }
|
||||||
|
ins { text-decoration: underline; color: #005100; }
|
||||||
|
|
||||||
|
p.example { margin-left: 2em; }
|
||||||
|
pre.example { margin-left: 2em; }
|
||||||
|
div.example { margin-left: 2em; }
|
||||||
|
|
||||||
|
code.extract { background-color: #F5F6A2; }
|
||||||
|
pre.extract { margin-left: 2em; background-color: #F5F6A2;
|
||||||
|
border: 1px solid #E1E28E; }
|
||||||
|
|
||||||
|
p.function { }
|
||||||
|
.attribute { margin-left: 2em; }
|
||||||
|
.attribute dt { float: left; font-style: italic;
|
||||||
|
padding-right: 1ex; }
|
||||||
|
.attribute dd { margin-left: 0em; }
|
||||||
|
|
||||||
|
blockquote.std { color: #000000; background-color: #F1F1F1;
|
||||||
|
border: 1px solid #D1D1D1;
|
||||||
|
padding-left: 0.5em; padding-right: 0.5em; }
|
||||||
|
blockquote.stddel { text-decoration: line-through;
|
||||||
|
color: #000000; background-color: #FFEBFF;
|
||||||
|
border: 1px solid #ECD7EC;
|
||||||
|
padding-left: 0.5empadding-right: 0.5em; ; }
|
||||||
|
|
||||||
|
blockquote.stdins { text-decoration: underline;
|
||||||
|
color: #000000; background-color: #C8FFC8;
|
||||||
|
border: 1px solid #B3EBB3; padding: 0.5em; }
|
||||||
|
|
||||||
|
table { border: 1px solid black; border-spacing: 0px;
|
||||||
|
margin-left: auto; margin-right: auto; }
|
||||||
|
th { text-align: left; vertical-align: top;
|
||||||
|
padding-left: 0.8em; border: none; }
|
||||||
|
td { text-align: left; vertical-align: top;
|
||||||
|
padding-left: 0.8em; border: none; }
|
||||||
|
|
||||||
|
</style>
|
||||||
|
|
||||||
</head>
|
</head>
|
||||||
<body>
|
<body>
|
||||||
<h1>Text Formatting</h1>
|
<h1>Text Formatting</h1>
|
||||||
@ -20,7 +62,8 @@ Victor Zverovich, victor.zverovich@gmail.com
|
|||||||
<a href="#Introduction">Introduction</a><br>
|
<a href="#Introduction">Introduction</a><br>
|
||||||
<a href="#Design">Design</a><br>
|
<a href="#Design">Design</a><br>
|
||||||
<a href="#Syntax">Format String Syntax</a><br>
|
<a href="#Syntax">Format String Syntax</a><br>
|
||||||
<a href="#Syntax">Locale Support</a><br>
|
<a href="#Extensibility">Extensibility</a><br>
|
||||||
|
<a href="#Locale">Locale Support</a><br>
|
||||||
<a href="#Wording">Wording</a><br>
|
<a href="#Wording">Wording</a><br>
|
||||||
<a href="#References">References</a><br>
|
<a href="#References">References</a><br>
|
||||||
</p>
|
</p>
|
||||||
@ -38,8 +81,8 @@ user-defined types.
|
|||||||
<p>
|
<p>
|
||||||
Example:
|
Example:
|
||||||
|
|
||||||
<pre>
|
<pre class="example">
|
||||||
<code>std::string message = std::format("The answer is {}.", 42)</code>
|
<code>std::string message = std::format("The answer is {}.", 42);</code>
|
||||||
</pre>
|
</pre>
|
||||||
|
|
||||||
<h2><a name="Design">Design</a></h2>
|
<h2><a name="Design">Design</a></h2>
|
||||||
@ -62,7 +105,7 @@ of issues:
|
|||||||
<li>There is no standard way to extend the syntax for user-defined types.</li>
|
<li>There is no standard way to extend the syntax for user-defined types.</li>
|
||||||
<li>There are subtle differences between different implementations. For example,
|
<li>There are subtle differences between different implementations. For example,
|
||||||
POSIX positional arguments <a href="#2">[2]</a> are not supported on
|
POSIX positional arguments <a href="#2">[2]</a> are not supported on
|
||||||
MSVC.</li>
|
some systems <a href="#6">[6]</a>.</li>
|
||||||
<li>Using <code>'%'</code> in a custom format specifier, e.g. for
|
<li>Using <code>'%'</code> in a custom format specifier, e.g. for
|
||||||
<code>put_time</code>-like time formatting, poses difficulties.</li>
|
<code>put_time</code>-like time formatting, poses difficulties.</li>
|
||||||
</ul>
|
</ul>
|
||||||
@ -94,10 +137,88 @@ and it is described in details in TODO:link. Here are some of the advantages:
|
|||||||
|
|
||||||
<p>
|
<p>
|
||||||
The syntax is expressive enough to enable translation, possibly automated,
|
The syntax is expressive enough to enable translation, possibly automated,
|
||||||
of most printf format strings. TODO: table of correspondence between
|
of most printf format strings. The correspondence between <code>printf</code>
|
||||||
printf and the new syntax
|
and the new syntax is given in the following table.
|
||||||
</p>
|
</p>
|
||||||
|
|
||||||
|
<table>
|
||||||
|
<thead>
|
||||||
|
<tr><th>printf</th><th>new</th><th>comment</th></tr>
|
||||||
|
</thead>
|
||||||
|
<tbody>
|
||||||
|
<tr><td>-</td><td><</td><td>left alignment</td></tr>
|
||||||
|
<tr><td>+</td><td>+</td><td></td></tr>
|
||||||
|
<tr><td><em>space</em></td><td><em>space</em></td><td></td></tr>
|
||||||
|
<tr><td>hh</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>h</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>l</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>ll</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>j</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>z</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>t</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>L</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>c</td><td>c (optional)</td><td></td></tr>
|
||||||
|
<tr><td>s</td><td>s (optional)</td><td></td></tr>
|
||||||
|
<tr><td>d</td><td>d (optional)</td><td></td></tr>
|
||||||
|
<tr><td>i</td><td>d (optional)</td><td></td></tr>
|
||||||
|
<tr><td>o</td><td>o</td><td></td></tr>
|
||||||
|
<tr><td>x</td><td>x</td><td></td></tr>
|
||||||
|
<tr><td>X</td><td>X</td><td></td></tr>
|
||||||
|
<tr><td>u</td><td>d (optional)</td><td></td></tr>
|
||||||
|
<tr><td>f</td><td>f</td><td></td></tr>
|
||||||
|
<tr><td>F</td><td>F</td><td></td></tr>
|
||||||
|
<tr><td>e</td><td>e</td><td></td></tr>
|
||||||
|
<tr><td>E</td><td>E</td><td></td></tr>
|
||||||
|
<tr><td>a</td><td>a</td><td></td></tr>
|
||||||
|
<tr><td>A</td><td>A</td><td></td></tr>
|
||||||
|
<tr><td>g</td><td>g (optional)</td><td></td></tr>
|
||||||
|
<tr><td>G</td><td>G</td><td></td></tr>
|
||||||
|
<tr><td>n</td><td>unused</td><td></td></tr>
|
||||||
|
<tr><td>p</td><td>p (optional)</td><td></td></tr>
|
||||||
|
</tbody>
|
||||||
|
</table>
|
||||||
|
|
||||||
|
<p>
|
||||||
|
Width and precision are represented similarly in <code>printf</code> and the
|
||||||
|
proposed syntax with the only difference that runtime value is specified by
|
||||||
|
<code>*</code> in the former and <code>{}</code> in the latter, possibly with
|
||||||
|
the index of the argument inside the braces.
|
||||||
|
</p>
|
||||||
|
|
||||||
|
<p>
|
||||||
|
As can be seen from the table above, most of the specifiers remain the same
|
||||||
|
which simplifies migration from <code>printf</code>. Notable difference is in
|
||||||
|
the alignment specification. The proposed syntax allows left, center, and right
|
||||||
|
alignment represented by <code>'<'</code>, <code>'^'</code>, and
|
||||||
|
<code>'>'</code> respectively which is more expressive than the corresponding
|
||||||
|
<code>printf</code> syntax.
|
||||||
|
</p>
|
||||||
|
|
||||||
|
<h3><a name="Extensibility">Extensibility</a></h3>
|
||||||
|
|
||||||
|
<p>
|
||||||
|
Both format string syntax and API are designed with extensibility in mind.
|
||||||
|
The mini-language can be extended for user-defined types and users can provide
|
||||||
|
functions that do parsing and formatting for such types.
|
||||||
|
</p>
|
||||||
|
|
||||||
|
<p>The general syntax of a replacement field in a format string is
|
||||||
|
|
||||||
|
<dl>
|
||||||
|
<dt><em>replacement-field</em>:</dt>
|
||||||
|
<dd>
|
||||||
|
<code>{</code> <em>integer<sub>opt</sub></em> <code>}</code><br/>
|
||||||
|
<code>{</code> <em>integer<sub>opt</sub></em>
|
||||||
|
<code>:</code> <em>format-spec</em> <code>}</code>
|
||||||
|
</dd>
|
||||||
|
</dl>
|
||||||
|
|
||||||
|
<p>
|
||||||
|
where <em>format-spec</em> is predefined for built-in types, but can be
|
||||||
|
customized for user-defined types. For example, time formatting
|
||||||
|
|
||||||
|
TODO: elaborate</p>
|
||||||
|
|
||||||
<h3><a name="Locale">Locale Support</a></h3>
|
<h3><a name="Locale">Locale Support</a></h3>
|
||||||
|
|
||||||
<p>TODO</p>
|
<p>TODO</p>
|
||||||
@ -106,8 +227,6 @@ printf and the new syntax
|
|||||||
|
|
||||||
<p>TODO</p>
|
<p>TODO</p>
|
||||||
|
|
||||||
<h2><a name="References">References</a></h2>
|
|
||||||
|
|
||||||
<h2><a name="Implementation">Implementation</a></h2>
|
<h2><a name="Implementation">Implementation</a></h2>
|
||||||
|
|
||||||
<p>
|
<p>
|
||||||
@ -115,6 +234,8 @@ The ideas proposed in this paper have been implemented in the open-source fmt
|
|||||||
library. TODO: link
|
library. TODO: link
|
||||||
</p>
|
</p>
|
||||||
|
|
||||||
|
<h2><a name="References">References</a></h2>
|
||||||
|
|
||||||
<p>
|
<p>
|
||||||
<a name="1">[1]</a>
|
<a name="1">[1]</a>
|
||||||
<cite>The <code>fprintf</code> function. ISO/IEC 9899:2011. 7.21.6.1.</cite><br/>
|
<cite>The <code>fprintf</code> function. ISO/IEC 9899:2011. 7.21.6.1.</cite><br/>
|
||||||
@ -131,6 +252,10 @@ String.Format Method</a>. .NET Framework Class Library.</cite><br/>
|
|||||||
<a name="5">[5]</a>
|
<a name="5">[5]</a>
|
||||||
<cite><a href="https://doc.rust-lang.org/std/fmt/">
|
<cite><a href="https://doc.rust-lang.org/std/fmt/">
|
||||||
Module <code>std::fmt</code></a>. The Rust Standard Library.</cite><br/>
|
Module <code>std::fmt</code></a>. The Rust Standard Library.</cite><br/>
|
||||||
|
<a name="6">[6]</a>
|
||||||
|
<cite><a href="https://msdn.microsoft.com/en-us/library/56e442dc(v=vs.120).aspx">
|
||||||
|
Format Specification Syntax: printf and wprintf Functions</a>. C++ Language and
|
||||||
|
Standard Libraries.</cite><br/>
|
||||||
</p>
|
</p>
|
||||||
|
|
||||||
</body>
|
</body>
|
||||||
|
|||||||
Reference in New Issue
Block a user