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| author | chai <chaifix@163.com> | 2021-10-30 11:32:16 +0800 |
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| committer | chai <chaifix@163.com> | 2021-10-30 11:32:16 +0800 |
| commit | 42ec7286b2d36a9ba22925f816a17cb1cc2aa5ce (patch) | |
| tree | 24bc7009457a8d7500f264e89946dc20d069294f /Data/Libraries/Penlight/docs/manual/08-additional.md.html | |
| parent | 164885fd98d48703bd771f802d79557b7db97431 (diff) | |
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diff --git a/Data/Libraries/Penlight/docs/manual/08-additional.md.html b/Data/Libraries/Penlight/docs/manual/08-additional.md.html new file mode 100644 index 0000000..d13ac6e --- /dev/null +++ b/Data/Libraries/Penlight/docs/manual/08-additional.md.html @@ -0,0 +1,815 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html> +<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/> +<head> + <title>Penlight Documentation</title> + <link rel="stylesheet" href="../ldoc_fixed.css" type="text/css" /> +</head> +<body> + +<div id="container"> + +<div id="product"> + <div id="product_logo"></div> + <div id="product_name"><big><b></b></big></div> + <div id="product_description"></div> +</div> <!-- id="product" --> + + +<div id="main"> + + +<!-- Menu --> + +<div id="navigation"> +<br/> +<h1>Penlight</h1> + +<ul> + <li><a href="https://github.com/lunarmodules/Penlight">GitHub Project</a></li> + <li><a href="../index.html">Documentation</a></li> +</ul> + +<h2>Contents</h2> +<ul> +<li><a href="#Simple_Input_Patterns">Simple Input Patterns </a></li> +<li><a href="#Command_line_Programs_with_Lapp">Command-line Programs with Lapp </a></li> +<li><a href="#Simple_Test_Framework">Simple Test Framework </a></li> +</ul> + + +<h2>Manual</h2> +<ul class="nowrap"> + <li><a href="../manual/01-introduction.md.html">Introduction</a></li> + <li><a href="../manual/02-arrays.md.html">Tables and Arrays</a></li> + <li><a href="../manual/03-strings.md.html">Strings. Higher-level operations on strings.</a></li> + <li><a href="../manual/04-paths.md.html">Paths and Directories</a></li> + <li><a href="../manual/05-dates.md.html">Date and Time</a></li> + <li><a href="../manual/06-data.md.html">Data</a></li> + <li><a href="../manual/07-functional.md.html">Functional Programming</a></li> + <li><strong>Additional Libraries</strong></li> + <li><a href="../manual/09-discussion.md.html">Technical Choices</a></li> +</ul> +<h2>Libraries</h2> +<ul class="nowrap"> + <li><a href="../libraries/pl.html">pl</a></li> + <li><a href="../libraries/pl.app.html">pl.app</a></li> + <li><a href="../libraries/pl.array2d.html">pl.array2d</a></li> + <li><a href="../libraries/pl.class.html">pl.class</a></li> + <li><a href="../libraries/pl.compat.html">pl.compat</a></li> + <li><a href="../libraries/pl.comprehension.html">pl.comprehension</a></li> + <li><a href="../libraries/pl.config.html">pl.config</a></li> + <li><a href="../libraries/pl.data.html">pl.data</a></li> + <li><a href="../libraries/pl.dir.html">pl.dir</a></li> + <li><a href="../libraries/pl.file.html">pl.file</a></li> + <li><a href="../libraries/pl.func.html">pl.func</a></li> + <li><a href="../libraries/pl.import_into.html">pl.import_into</a></li> + <li><a href="../libraries/pl.input.html">pl.input</a></li> + <li><a href="../libraries/pl.lapp.html">pl.lapp</a></li> + <li><a href="../libraries/pl.lexer.html">pl.lexer</a></li> + <li><a href="../libraries/pl.luabalanced.html">pl.luabalanced</a></li> + <li><a href="../libraries/pl.operator.html">pl.operator</a></li> + <li><a href="../libraries/pl.path.html">pl.path</a></li> + <li><a href="../libraries/pl.permute.html">pl.permute</a></li> + <li><a href="../libraries/pl.pretty.html">pl.pretty</a></li> + <li><a href="../libraries/pl.seq.html">pl.seq</a></li> + <li><a href="../libraries/pl.sip.html">pl.sip</a></li> + <li><a href="../libraries/pl.strict.html">pl.strict</a></li> + <li><a href="../libraries/pl.stringio.html">pl.stringio</a></li> + <li><a href="../libraries/pl.stringx.html">pl.stringx</a></li> + <li><a href="../libraries/pl.tablex.html">pl.tablex</a></li> + <li><a href="../libraries/pl.template.html">pl.template</a></li> + <li><a href="../libraries/pl.test.html">pl.test</a></li> + <li><a href="../libraries/pl.text.html">pl.text</a></li> + <li><a href="../libraries/pl.types.html">pl.types</a></li> + <li><a href="../libraries/pl.url.html">pl.url</a></li> + <li><a href="../libraries/pl.utils.html">pl.utils</a></li> + <li><a href="../libraries/pl.xml.html">pl.xml</a></li> +</ul> +<h2>Classes</h2> +<ul class="nowrap"> + <li><a href="../classes/pl.Date.html">pl.Date</a></li> + <li><a href="../classes/pl.List.html">pl.List</a></li> + <li><a href="../classes/pl.Map.html">pl.Map</a></li> + <li><a href="../classes/pl.MultiMap.html">pl.MultiMap</a></li> + <li><a href="../classes/pl.OrderedMap.html">pl.OrderedMap</a></li> + <li><a href="../classes/pl.Set.html">pl.Set</a></li> +</ul> +<h2>Examples</h2> +<ul class="nowrap"> + <li><a href="../examples/seesubst.lua.html">seesubst.lua</a></li> + <li><a href="../examples/sipscan.lua.html">sipscan.lua</a></li> + <li><a href="../examples/symbols.lua.html">symbols.lua</a></li> + <li><a href="../examples/test-cmp.lua.html">test-cmp.lua</a></li> + <li><a href="../examples/test-data.lua.html">test-data.lua</a></li> + <li><a href="../examples/test-listcallbacks.lua.html">test-listcallbacks.lua</a></li> + <li><a href="../examples/test-pretty.lua.html">test-pretty.lua</a></li> + <li><a href="../examples/test-symbols.lua.html">test-symbols.lua</a></li> + <li><a href="../examples/testclone.lua.html">testclone.lua</a></li> + <li><a href="../examples/testconfig.lua.html">testconfig.lua</a></li> + <li><a href="../examples/testglobal.lua.html">testglobal.lua</a></li> + <li><a href="../examples/testinputfields.lua.html">testinputfields.lua</a></li> + <li><a href="../examples/testinputfields2.lua.html">testinputfields2.lua</a></li> + <li><a href="../examples/testxml.lua.html">testxml.lua</a></li> + <li><a href="../examples/which.lua.html">which.lua</a></li> +</ul> + +</div> + +<div id="content"> + + +<h2>Additional Libraries</h2> + +<p>Libraries in this section are no longer considered to be part of the Penlight +core, but still provide specialized functionality when needed.</p> + +<p><a id="sip"/></p> + +<p><a name="Simple_Input_Patterns"></a></p> +<h3>Simple Input Patterns</h3> + +<p>Lua string pattern matching is very powerful, and usually you will not need a +traditional regular expression library. Even so, sometimes Lua code ends up +looking like Perl, which happens because string patterns are not always the +easiest things to read, especially for the casual reader. Here is a program +which needs to understand three distinct date formats:</p> + + +<pre> +<span class="comment">-- parsing dates using Lua string patterns +</span>months={Jan=<span class="number">1</span>,Feb=<span class="number">2</span>,Mar=<span class="number">3</span>,Apr=<span class="number">4</span>,May=<span class="number">5</span>,Jun=<span class="number">6</span>, +Jul=<span class="number">7</span>,Aug=<span class="number">8</span>,Sep=<span class="number">9</span>,Oct=<span class="number">10</span>,Nov=<span class="number">11</span>,Dec=<span class="number">12</span>} + +<span class="keyword">function</span> check_and_process(d,m,y) + d = <span class="global">tonumber</span>(d) + m = <span class="global">tonumber</span>(m) + y = <span class="global">tonumber</span>(y) + .... +<span class="keyword">end</span> + +<span class="keyword">for</span> line <span class="keyword">in</span> f:lines() <span class="keyword">do</span> + <span class="comment">-- ordinary (English) date format +</span> <span class="keyword">local</span> d,m,y = line:match(<span class="string">'(%d+)/(%d+)/(%d+)'</span>) + <span class="keyword">if</span> d <span class="keyword">then</span> + check_and_process(d,m,y) + <span class="keyword">else</span> <span class="comment">-- ISO date?? +</span> y,m,d = line:match(<span class="string">'(%d+)%-(%d+)%-(%d+)'</span>) + <span class="keyword">if</span> y <span class="keyword">then</span> + check_and_process(d,m,y) + <span class="keyword">else</span> <span class="comment">-- <day> <month-name> <year>? +</span> d,mm,y = line:match(<span class="string">'%(d+)%s+(%a+)%s+(%d+)'</span>) + m = months[mm] + check_and_process(d,m,y) + <span class="keyword">end</span> + <span class="keyword">end</span> +<span class="keyword">end</span> +</pre> + +<p>These aren't particularly difficult patterns, but already typical issues are +appearing, such as having to escape '-'. Also, <a href="https://www.lua.org/manual/5.1/manual.html#pdf-string.match">string.match</a> returns its +captures, so that we're forced to use a slightly awkward nested if-statement.</p> + +<p>Verification issues will further cloud the picture, since regular expression +people try to enforce constraints (like year cannot be more than four digits) +using regular expressions, on the usual grounds that you shouldn't stop using a +hammer when you are enjoying yourself.</p> + +<p><a href="../libraries/pl.sip.html#">pl.sip</a> provides a simple, intuitive way to detect patterns in strings and +extract relevant parts.</p> + + +<pre> +> sip = <span class="global">require</span> <span class="string">'pl.sip'</span> +> dump = <span class="global">require</span>(<span class="string">'pl.pretty'</span>).dump +> res = {} +> c = sip.compile <span class="string">'ref=$S{file}:$d{line}'</span> +> = c(<span class="string">'ref=hello.c:10'</span>,res) +<span class="keyword">true</span> +> dump(res) +{ + line = <span class="number">10</span>, + file = <span class="string">"hello.c"</span> +} +> = c(<span class="string">'ref=long name, no line'</span>,res) +<span class="keyword">false</span> +</pre> + +<p><a href="../libraries/pl.sip.html#compile">sip.compile</a> creates a pattern matcher function, which takes a string and a +table as arguments. If the string matches the pattern, then <code>true</code> is returned +and the table is populated according to the captures within the pattern.</p> + +<p>Here is another version of the date parser:</p> + + +<pre> +<span class="comment">-- using SIP patterns +</span><span class="keyword">function</span> check(t) + check_and_process(t.day,t.month,t.year) +<span class="keyword">end</span> + +shortdate = sip.compile(<span class="string">'$d{day}/$d{month}/$d{year}'</span>) +longdate = sip.compile(<span class="string">'$d{day} $v{mon} $d{year}'</span>) +isodate = sip.compile(<span class="string">'$d{year}-$d{month}-$d{day}'</span>) + +<span class="keyword">for</span> line <span class="keyword">in</span> f:lines() <span class="keyword">do</span> + <span class="keyword">local</span> res = {} + <span class="keyword">if</span> shortdate(str,res) <span class="keyword">then</span> + check(res) + <span class="keyword">elseif</span> isodate(str,res) <span class="keyword">then</span> + check(res) + <span class="keyword">elseif</span> longdate(str,res) <span class="keyword">then</span> + res.month = months[res.mon] + check(res) + <span class="keyword">end</span> +<span class="keyword">end</span> +</pre> + +<p>SIP captures start with '$', then a one-character type, and then an +optional variable name in curly braces.</p> + + +<pre> +Type Meaning +v identifier +i possibly signed integer +f floating-point number +r rest of line +q quoted <span class="global">string</span> (quoted using either ' <span class="keyword">or</span> ") +p a path name +( anything inside balanced parentheses +[ anything inside balanced brackets +{ anything inside balanced curly brackets +< anything inside balanced angle brackets +</pre> + +<p>If a type is not one of the above, then it's assumed to be one of the standard +Lua character classes, and will match one or more repetitions of that class. +Any spaces you leave in your pattern will match any number of spaces, including +zero, unless the spaces are between two identifier characters or patterns +matching them; in that case, at least one space will be matched.</p> + +<p>SIP captures (like <code>$v{mon}</code>) do not have to be named. You can use just <code>$v</code>, but +you have to be consistent; if a pattern contains unnamed captures, then all +captures must be unnamed. In this case, the result table is a simple list of +values.</p> + +<p><a href="../libraries/pl.sip.html#match">sip.match</a> is a useful shortcut if you want to compile and match in one call, +without saving the compiled pattern. It caches the result, so it is not much +slower than explicitly using <a href="../libraries/pl.sip.html#compile">sip.compile</a>.</p> + + +<pre> +> sip.match(<span class="string">'($q{first},$q{second})'</span>,<span class="string">'("john","smith")'</span>,res) +<span class="keyword">true</span> +> res +{second=<span class="string">'smith'</span>,first=<span class="string">'john'</span>} +> res = {} +> sip.match(<span class="string">'($q,$q)'</span>,<span class="string">'("jan","smit")'</span>,res) <span class="comment">-- unnamed captures +</span><span class="keyword">true</span> +> res +{<span class="string">'jan'</span>,<span class="string">'smit'</span>} +> sip.match(<span class="string">'($q,$q)'</span>,<span class="string">'("jan", "smit")'</span>,res) +<span class="keyword">false</span> <span class="comment">---> oops! Can't handle extra space! +</span>> sip.match(<span class="string">'( $q , $q )'</span>,<span class="string">'("jan", "smit")'</span>,res) +<span class="keyword">true</span> +</pre> + +<p>As a general rule, allow for whitespace in your patterns.</p> + +<p>Finally, putting a '$' at the end of a pattern means 'capture the rest of the +line, starting at the first non-space'. It is a shortcut for '$r{rest}', +or just '$r' if no named captures are used.</p> + + +<pre> +> sip.match(<span class="string">'( $q , $q ) $'</span>,<span class="string">'("jan", "smit") and a string'</span>,res) +<span class="keyword">true</span> +> res +{<span class="string">'jan'</span>,<span class="string">'smit'</span>,<span class="string">'and a string'</span>} +> res = {} +> sip.match(<span class="string">'( $q{first} , $q{last} ) $'</span>,<span class="string">'("jan", "smit") and a string'</span>,res) +<span class="keyword">true</span> +> res +{first=<span class="string">'jan'</span>,rest=<span class="string">'and a string'</span>,last=<span class="string">'smit'</span>} +</pre> + +<p><a id="lapp"/></p> + +<p><a name="Command_line_Programs_with_Lapp"></a></p> +<h3>Command-line Programs with Lapp</h3> + +<p><a href="../libraries/pl.lapp.html#">pl.lapp</a> is a small and focused Lua module which aims to make standard +command-line parsing easier and intuitive. It implements the standard GNU style, +i.e. short flags with one letter start with '-', and there may be an additional +long flag which starts with '--'. Generally options which take an argument expect +to find it as the next parameter (e.g. 'gcc test.c -o test') but single short +options taking a value can dispense with the space (e.g. 'head -n4 +test.c' or <code>gcc -I/usr/include/lua/5.1 ...</code>)</p> + +<p>As far as possible, Lapp will convert parameters into their equivalent Lua types, +i.e. convert numbers and convert filenames into file objects. If any conversion +fails, or a required parameter is missing, an error will be issued and the usage +text will be written out. So there are two necessary tasks, supplying the flag +and option names and associating them with a type.</p> + +<p>For any non-trivial script, even for personal consumption, it's necessary to +supply usage text. The novelty of Lapp is that it starts from that point and +defines a loose format for usage strings which can specify the names and types of +the parameters.</p> + +<p>An example will make this clearer:</p> + + +<pre> +<span class="comment">-- scale.lua +</span> lapp = <span class="global">require</span> <span class="string">'pl.lapp'</span> + <span class="keyword">local</span> args = lapp <span class="string">[[ + Does some calculations + -o,--offset (default 0.0) Offset to add to scaled number + -s,--scale (number) Scaling factor + <number> (number) Number to be scaled + ]]</span> + + <span class="global">print</span>(args.offset + args.scale * args.number) +</pre> + +<p>Here is a command-line session using this script:</p> + + +<pre> +$ lua scale.lua +scale.lua:missing required parameter: scale + +Does some calculations + -o,<span class="comment">--offset (default 0.0) Offset to add to scaled number +</span> -s,<span class="comment">--scale (number) Scaling factor +</span> <number> (number ) Number to be scaled + +$ lua scale.lua -s <span class="number">2.2</span> <span class="number">10</span> +<span class="number">22</span> + +$ lua scale.lua -s <span class="number">2.2</span> x10 +scale.lua:unable to convert to number: x10 + +....(usage as before) +</pre> + +<p>There are two kinds of lines in Lapp usage strings which are meaningful; option +and parameter lines. An option line gives the short option, optionally followed +by the corresponding long option. A type specifier in parentheses may follow. +Similarly, a parameter line starts with '<NAME>', followed by a type +specifier.</p> + +<p>Type specifiers usually start with a type name: one of 'boolean', 'string','number','file-in' or +'file-out'. You may leave this out, but then <em>must</em> say 'default' followed by a value. +If a flag or parameter has a default, it is not <em>required</em> and is set to the default. The actual +type is deduced from this value (number, string, file or boolean) if not provided directly. +'Deduce' is a fancy word for 'guess' and it can be wrong, e.g '(default 1)' +will always be a number. You can say '(string default 1)' to override the guess. +There are file values for the predefined console streams: stdin, stdout, stderr.</p> + +<p>The boolean type is the default for flags. Not providing the type specifier is equivalent to +'(boolean default false)`. If the flag is meant to be 'turned off' then either the full +'(boolean default true)` or the shortcut '(default true)' will work.</p> + +<p>An alternative to <code>default</code> is <code>optional</code>:</p> + + +<pre> +<span class="keyword">local</span> lapp = <span class="global">require</span> <span class="string">'pl.lapp'</span> +<span class="keyword">local</span> args = lapp <span class="string">[[ + --cmd (optional string) Command to run. +]]</span> + +<span class="keyword">if</span> args.cmd <span class="keyword">then</span> + <span class="global">os</span>.execute(args.cmd) +<span class="keyword">end</span> +</pre> + +<p>Here we're implying that <code>cmd</code> need not be specified (just as with <code>default</code>) but if not +present, then <code>args.cmd</code> is <code>nil</code>, which will always test false.</p> + +<p>The rest of the line is ignored and can be used for explanatory text.</p> + +<p>This script shows the relation between the specified parameter names and the +fields in the output table.</p> + + +<pre> +<span class="comment">-- simple.lua +</span><span class="keyword">local</span> args = <span class="global">require</span> (<span class="string">'pl.lapp'</span>) <span class="string">[[ +Various flags and option types + -p A simple optional flag, defaults to false + -q,--quiet A simple flag with long name + -o (string) A required option with argument + -s (default 'save') Optional string with default 'save' (single quotes ignored) + -n (default 1) Optional numerical flag with default 1 + -b (string default 1) Optional string flag with default '1' (type explicit) + <input> (default stdin) Optional input file parameter, reads from stdin +]]</span> + +<span class="keyword">for</span> k,v <span class="keyword">in</span> <span class="global">pairs</span>(args) <span class="keyword">do</span> + <span class="global">print</span>(k,v) +<span class="keyword">end</span> +</pre> + +<p>I've just dumped out all values of the args table; note that args.quiet has +become true, because it's specified; args.p defaults to false. If there is a long +name for an option, that will be used in preference as a field name. A type or +default specifier is not necessary for simple flags, since the default type is +boolean.</p> + + +<pre> +$ simple -o test -q simple.lua +p <span class="keyword">false</span> +input file (<span class="number">781</span>C1BD8) +quiet <span class="keyword">true</span> +o test +input_name simple.lua +D:\dev\lua\lapp>simple -o test simple.lua one two three +<span class="number">1</span> one +<span class="number">2</span> two +<span class="number">3</span> three +p <span class="keyword">false</span> +quiet <span class="keyword">false</span> +input file (<span class="number">781</span>C1BD8) +o test +input_name simple.lua +</pre> + +<p>The parameter input has been set to an open read-only file object - we know it +must be a read-only file since that is the type of the default value. The field +input_name is automatically generated, since it's often useful to have access to +the original filename.</p> + +<p>Notice that any extra parameters supplied will be put in the result table with +integer indices, i.e. args[i] where i goes from 1 to #args.</p> + +<p>Files don't really have to be closed explicitly for short scripts with a quick +well-defined mission, since the result of garbage-collecting file objects is to +close them.</p> + +<h4>Enforcing a Range and Enumerations</h4> + +<p>The type specifier can also be of the form '(' MIN '..' MAX ')' or a set of strings +separated by '|'.</p> + + +<pre> +<span class="keyword">local</span> lapp = <span class="global">require</span> <span class="string">'pl.lapp'</span> +<span class="keyword">local</span> args = lapp <span class="string">[[ + Setting ranges + <x> (1..10) A number from 1 to 10 + <y> (-5..1e6) Bigger range + <z> (slow|medium|fast) +]]</span> + +<span class="global">print</span>(args.x,args.y) +</pre> + +<p>Here the meaning of ranges is that the value is greater or equal to MIN and less or equal +to MAX. +An 'enum' is a <em>string</em> that can only have values from a specified set.</p> + +<h4>Custom Types</h4> + +<p>There is no builti-in way to force a parameter to be a whole number, but +you may define a custom type that does this:</p> + + +<pre> +lapp = <span class="global">require</span> (<span class="string">'pl.lapp'</span>) + +lapp.add_type(<span class="string">'integer'</span>,<span class="string">'number'</span>, + <span class="keyword">function</span>(x) + lapp.<span class="global">assert</span>(<span class="global">math</span>.ceil(x) == x, <span class="string">'not an integer!'</span>) + <span class="keyword">end</span> +) + +<span class="keyword">local</span> args = lapp <span class="string">[[ + <ival> (integer) Process PID +]]</span> + +<span class="global">print</span>(args.ival) +</pre> + +<p><a href="../libraries/pl.lapp.html#add_type">lapp.add_type</a> takes three parameters, a type name, a converter and a constraint +function. The constraint function is expected to throw an assertion if some +condition is not true; we use <a href="../libraries/pl.lapp.html#assert">lapp.assert</a> because it fails in the standard way +for a command-line script. The converter argument can either be a type name known +to Lapp, or a function which takes a string and generates a value.</p> + +<p>Here's a useful custom type that allows dates to be input as <a href="../classes/pl.Date.html#">pl.Date</a> values:</p> + + +<pre> +<span class="keyword">local</span> df = Date.Format() + +lapp.add_type(<span class="string">'date'</span>, + <span class="keyword">function</span>(s) + <span class="keyword">local</span> d,e = df:parse(s) + lapp.<span class="global">assert</span>(d,e) + <span class="keyword">return</span> d + <span class="keyword">end</span> +) +</pre> + +<h4>'varargs' Parameter Arrays</h4> + + +<pre> +lapp = <span class="global">require</span> <span class="string">'pl.lapp'</span> +<span class="keyword">local</span> args = lapp <span class="string">[[ +Summing numbers + <numbers...> (number) A list of numbers to be summed +]]</span> + +<span class="keyword">local</span> sum = <span class="number">0</span> +<span class="keyword">for</span> i,x <span class="keyword">in</span> <span class="global">ipairs</span>(args.numbers) <span class="keyword">do</span> + sum = sum + x +<span class="keyword">end</span> +<span class="global">print</span> (<span class="string">'sum is '</span>..sum) +</pre> + +<p>The parameter number has a trailing '...', which indicates that this parameter is +a 'varargs' parameter. It must be the last parameter, and args.number will be an +array.</p> + +<p>Consider this implementation of the head utility from Mac OS X:</p> + + +<pre> +<span class="comment">-- implements a BSD-style head +</span><span class="comment">-- (see http://www.manpagez.com/man/1/head/osx-10.3.php) +</span> +lapp = <span class="global">require</span> (<span class="string">'pl.lapp'</span>) + +<span class="keyword">local</span> args = lapp <span class="string">[[ +Print the first few lines of specified files + -n (default 10) Number of lines to print + <files...> (default stdin) Files to print +]]</span> + +<span class="comment">-- by default, lapp converts file arguments to an actual Lua file object. +</span><span class="comment">-- But the actual filename is always available as <file>_name. +</span><span class="comment">-- In this case, 'files' is a varargs array, so that 'files_name' is +</span><span class="comment">-- also an array. +</span><span class="keyword">local</span> nline = args.n +<span class="keyword">local</span> nfile = #args.files +<span class="keyword">for</span> i = <span class="number">1</span>,nfile <span class="keyword">do</span> + <span class="keyword">local</span> file = args.files[i] + <span class="keyword">if</span> nfile > <span class="number">1</span> <span class="keyword">then</span> + <span class="global">print</span>(<span class="string">'==> '</span>..args.files_name[i]..<span class="string">' <=='</span>) + <span class="keyword">end</span> + <span class="keyword">local</span> n = <span class="number">0</span> + <span class="keyword">for</span> line <span class="keyword">in</span> file:lines() <span class="keyword">do</span> + <span class="global">print</span>(line) + n = n + <span class="number">1</span> + <span class="keyword">if</span> n == nline <span class="keyword">then</span> <span class="keyword">break</span> <span class="keyword">end</span> + <span class="keyword">end</span> +<span class="keyword">end</span> +</pre> + +<p>Note how we have access to all the filenames, because the auto-generated field +<code>files_name</code> is also an array!</p> + +<p>(This is probably not a very considerate script, since Lapp will open all the +files provided, and only close them at the end of the script. See the <code>xhead.lua</code> +example for another implementation.)</p> + +<p>Flags and options may also be declared as vararg arrays, and can occur anywhere. +If there is both a short and long form, then the trailing "..." must happen after the long form, +for example "-x,--network... (string)...",</p> + +<p>Bear in mind that short options can be combined (like 'tar -xzf'), so it's +perfectly legal to have '-vvv'. But normally the value of args.v is just a simple +<code>true</code> value.</p> + + +<pre> +<span class="keyword">local</span> args = <span class="global">require</span> (<span class="string">'pl.lapp'</span>) <span class="string">[[ + -v... Verbosity level; can be -v, -vv or -vvv +]]</span> +vlevel = <span class="keyword">not</span> args.v[<span class="number">1</span>] <span class="keyword">and</span> <span class="number">0</span> <span class="keyword">or</span> #args.v +<span class="global">print</span>(vlevel) +</pre> + +<p>The vlevel assigment is a bit of Lua voodoo, so consider the cases:</p> + + +<pre> +* No -v flag, v is just { <span class="keyword">false</span> } +* One -v flags, v is { <span class="keyword">true</span> } +* Two -v flags, v is { <span class="keyword">true</span>, <span class="keyword">true</span> } +* Three -v flags, v is { <span class="keyword">true</span>, <span class="keyword">true</span>, <span class="keyword">true</span> } +</pre> + +<h4>Defining a Parameter Callback</h4> + +<p>If a script implements <code>lapp.callback</code>, then Lapp will call it after each +argument is parsed. The callback is passed the parameter name, the raw unparsed +value, and the result table. It is called immediately after assignment of the +value, so the corresponding field is available.</p> + + +<pre> +lapp = <span class="global">require</span> (<span class="string">'pl.lapp'</span>) + +<span class="keyword">function</span> lapp.callback(parm,arg,args) + <span class="global">print</span>(<span class="string">'+'</span>,parm,arg) +<span class="keyword">end</span> + +<span class="keyword">local</span> args = lapp <span class="string">[[ +Testing parameter handling + -p Plain flag (defaults to false) + -q,--quiet Plain flag with GNU-style optional long name + -o (string) Required string option + -n (number) Required number option + -s (default 1.0) Option that takes a number, but will default + <start> (number) Required number argument + <input> (default stdin) A parameter which is an input file + <output> (default stdout) One that is an output file +]]</span> +<span class="global">print</span> <span class="string">'args'</span> +<span class="keyword">for</span> k,v <span class="keyword">in</span> <span class="global">pairs</span>(args) <span class="keyword">do</span> + <span class="global">print</span>(k,v) +<span class="keyword">end</span> +</pre> + +<p>This produces the following output:</p> + + +<pre> +$ args -o name -n <span class="number">2</span> <span class="number">10</span> args.lua ++ o name ++ n <span class="number">2</span> ++ start <span class="number">10</span> ++ input args.lua +args +p <span class="keyword">false</span> +s <span class="number">1</span> +input_name args.lua +quiet <span class="keyword">false</span> +output file (<span class="number">781</span>C1B98) +start <span class="number">10</span> +input file (<span class="number">781</span>C1BD8) +o name +n <span class="number">2</span> +</pre> + +<p>Callbacks are needed when you want to take action immediately on parsing an +argument.</p> + +<h4>Slack Mode</h4> + +<p>If you'd like to use a multi-letter 'short' parameter you need to set +the <code>lapp.slack</code> variable to <code>true</code>.</p> + +<p>In the following example we also see how default <code>false</code> and default <code>true</code> flags can be used +and how to overwrite the default <code>-h</code> help flag (<code>--help</code> still works fine) - this applies +to non-slack mode as well.</p> + + +<pre> +<span class="comment">-- Parsing the command line ---------------------------------------------------- +</span><span class="comment">-- test.lua +</span><span class="keyword">local</span> lapp = <span class="global">require</span> <span class="string">'pl.lapp'</span> +<span class="keyword">local</span> pretty = <span class="global">require</span> <span class="string">'pl.pretty'</span> +lapp.slack = <span class="keyword">true</span> +<span class="keyword">local</span> args = lapp <span class="string">[[ +Does some calculations + -v, --video (string) Specify input video + -w, --width (default 256) Width of the video + -h, --height (default 144) Height of the video + -t, --time (default 10) Seconds of video to process + -sk,--seek (default 0) Seek number of seconds + -f1,--flag1 A false flag + -f2,--flag2 A false flag + -f3,--flag3 (default true) A true flag + -f4,--flag4 (default true) A true flag +]]</span> + +pretty.dump(args) +</pre> + +<p>And here we can see the output of <code>test.lua</code>:</p> + + +<pre> +$> lua test.lua -v abc <span class="comment">--time 40 -h 20 -sk 15 --flag1 -f3 +</span><span class="comment">----> +</span>{ + width = <span class="number">256</span>, + flag1 = <span class="keyword">true</span>, + flag3 = <span class="keyword">false</span>, + seek = <span class="number">15</span>, + flag2 = <span class="keyword">false</span>, + video = abc, + time = <span class="number">40</span>, + height = <span class="number">20</span>, + flag4 = <span class="keyword">true</span> +} +</pre> + +<p><a name="Simple_Test_Framework"></a></p> +<h3>Simple Test Framework</h3> + +<p><a href="../libraries/pl.test.html#">pl.test</a> was originally developed for the sole purpose of testing Penlight itself, +but you may find it useful for your own applications. (<a href="http://lua-users.org/wiki/UnitTesting">There are many other options</a>.)</p> + +<p>Most of the goodness is in <a href="../libraries/pl.test.html#asserteq">test.asserteq</a>. It uses <a href="../libraries/pl.tablex.html#deepcompare">tablex.deepcompare</a> on its two arguments, +and by default quits the test application with a non-zero exit code, and an informative +message printed to stderr:</p> + + +<pre> +<span class="keyword">local</span> test = <span class="global">require</span> <span class="string">'pl.test'</span> + +test.asserteq({<span class="number">10</span>,<span class="number">20</span>,<span class="number">30</span>},{<span class="number">10</span>,<span class="number">20</span>,<span class="number">30.1</span>}) + +<span class="comment">--~ test-test.lua:3: assertion failed +</span><span class="comment">--~ got: { +</span><span class="comment">--~ [1] = 10, +</span><span class="comment">--~ [2] = 20, +</span><span class="comment">--~ [3] = 30 +</span><span class="comment">--~ } +</span><span class="comment">--~ needed: { +</span><span class="comment">--~ [1] = 10, +</span><span class="comment">--~ [2] = 20, +</span><span class="comment">--~ [3] = 30.1 +</span><span class="comment">--~ } +</span><span class="comment">--~ these values were not equal</span> +</pre> + +<p>This covers most cases but it's also useful to compare strings using <a href="https://www.lua.org/manual/5.1/manual.html#pdf-string.match">string.match</a></p> + + +<pre> +<span class="comment">-- must start with bonzo the dog +</span>test.assertmatch (<span class="string">'bonzo the dog is here'</span>,<span class="string">'^bonzo the dog'</span>) +<span class="comment">-- must end with an integer +</span>test.assertmatch (<span class="string">'hello 42'</span>,<span class="string">'%d+$'</span>) +</pre> + +<p>Since Lua errors are usually strings, this matching strategy is used to test 'exceptions':</p> + + +<pre> +test.assertraise(<span class="keyword">function</span>() + <span class="keyword">local</span> t = <span class="keyword">nil</span> + <span class="global">print</span>(t.bonzo) +<span class="keyword">end</span>,<span class="string">'nil value'</span>) +</pre> + +<p>(Some care is needed to match the essential part of the thrown error if you care +for portability, since in Lua 5.2 +the exact error is "attempt to index local 't' (a nil value)" and in Lua 5.3 the error +is "attempt to index a nil value (local 't')")</p> + +<p>There is an extra optional argument to these test functions, which is helpful when writing +test helper functions. There you want to highlight the failed line, not the actual call +to <code>asserteq</code> or <code>assertmatch</code> - line 33 here is the call to <code>is_iden</code></p> + + +<pre> +<span class="keyword">function</span> is_iden(str) + test.assertmatch(str,<span class="string">'^[%a_][%w_]*$'</span>,<span class="number">1</span>) +<span class="keyword">end</span> + +is_iden <span class="string">'alpha_dog'</span> +is_iden <span class="string">'$dollars'</span> + +<span class="comment">--~ test-test.lua:33: assertion failed +</span><span class="comment">--~ got: "$dollars" +</span><span class="comment">--~ needed: "^[%a_][%w_]*$" +</span><span class="comment">--~ these strings did not match</span> +</pre> + +<p>Useful Lua functions often return multiple values, and <a href="../libraries/pl.test.html#tuple">test.tuple</a> is a convenient way to +capture these values, whether they contain nils or not.</p> + + +<pre> +T = test.tuple + +<span class="comment">--- common error pattern +</span><span class="keyword">function</span> failing() + <span class="keyword">return</span> <span class="keyword">nil</span>,<span class="string">'failed'</span> +<span class="keyword">end</span> + +test.asserteq(T(failing()),T(<span class="keyword">nil</span>,<span class="string">'failed'</span>)) +</pre> + + + +</div> <!-- id="content" --> +</div> <!-- id="main" --> +<div id="about"> +<i>generated by <a href="http://github.com/stevedonovan/LDoc">LDoc 1.4.6</a></i> +</div> <!-- id="about" --> +</div> <!-- id="container" --> +</body> +</html> |