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author Franklin Schmidt <fschmidt@gmail.com>
date Sun, 10 May 2015 16:09:45 -0600
parents f4aca5a5346a
children 7ac0891718eb
comparison
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473:bab5607a0eed 474:00646edc9d92
1935 <p> 1935 <p>
1936 Could be defined as: 1936 Could be defined as:
1937 1937
1938 <p><tt><pre> 1938 <p><tt><pre>
1939 function Luan.do_file(uri) 1939 function Luan.do_file(uri)
1940 return Luan.load_file(uri)() 1940 return <a href="#Luan.load_file">Luan.load_file</a>(uri)()
1941 end 1941 end
1942 </pre></tt></p> 1942 </pre></tt></p>
1943 1943
1944 1944
1945 1945
1957 if the table's metatable has a <tt>"__metatable"</tt> field, 1957 if the table's metatable has a <tt>"__metatable"</tt> field,
1958 returns the associated value. 1958 returns the associated value.
1959 Otherwise, returns the metatable of the given table. 1959 Otherwise, returns the metatable of the given table.
1960 1960
1961 1961
1962 1962 <h4 margin-top="1em"><a name="Luan.ipairs"><tt>Luan.ipairs (t)</tt></a></h4>
1963 1963
1964 <p> 1964 <p>
1965 <hr><h3><a name="pdf-ipairs"><code>ipairs (t)</code></a></h3> 1965 Returns an iterator function
1966
1967
1968 <p>
1969 Returns three values (an iterator function, the table <code>t</code>, and 0)
1970 so that the construction 1966 so that the construction
1971 1967
1972 <pre> 1968 <p><tt><pre>
1973 for i,v in ipairs(t) do <em>body</em> end 1969 for i,v in ipairs(t) do <i>body</i> end
1974 </pre><p> 1970 </pre></tt></p>
1971
1972 <p>
1975 will iterate over the key&ndash;value pairs 1973 will iterate over the key&ndash;value pairs
1976 (<code>1,t[1]</code>), (<code>2,t[2]</code>), ..., 1974 (<tt>1,t[1]</tt>), (<tt>2,t[2]</tt>), ...,
1977 up to the first nil value. 1975 up to the first nil value.
1978 1976
1979 1977 <p>
1980 1978 Could be defined as:
1981 1979
1982 <p> 1980 <p><tt><pre>
1983 <hr><h3><a name="pdf-load"><code>load (chunk [, chunkname [, mode [, env]]])</code></a></h3> 1981 function Luan.ipairs(t)
1984 1982 local i = 0
1983 return function()
1984 if i < #t then
1985 i = i + 1
1986 return i, t[i]
1987 end
1988 end
1989 end
1990 </pre></tt></p>
1991
1992
1993
1994 <h4 margin-top="1em"><a name="Luan.load"><tt>Luan.load (text, source_name [env, [, allow_expression]])</tt></a></h4>
1985 1995
1986 <p> 1996 <p>
1987 Loads a chunk. 1997 Loads a chunk.
1988 1998
1989 1999 <p>
1990 <p> 2000 The <tt>text</tt> is compiled.
1991 If <code>chunk</code> is a string, the chunk is this string.
1992 If <code>chunk</code> is a function,
1993 <code>load</code> calls it repeatedly to get the chunk pieces.
1994 Each call to <code>chunk</code> must return a string that concatenates
1995 with previous results.
1996 A return of an empty string, <b>nil</b>, or no value signals the end of the chunk.
1997
1998
1999 <p>
2000 If there are no syntactic errors, 2001 If there are no syntactic errors,
2001 returns the compiled chunk as a function; 2002 returns the compiled chunk as a function;
2002 otherwise, returns <b>nil</b> plus the error message. 2003 otherwise, throws an error.
2003 2004
2004 2005 <p>
2005 <p> 2006 The <tt>source_name</tt> parameter is a string saying where the text came from. It is used to produce error messages.
2006 If the resulting function has upvalues, 2007
2007 the first upvalue is set to the value of <code>env</code>, 2008 <p>
2008 if that parameter is given, 2009 If the <tt>env</tt> parameter is supplied, it becomes the <tt>_ENV</tt> of the chunk.
2009 or to the value of the global environment. 2010
2010 Other upvalues are initialized with <b>nil</b>. 2011 <p>
2011 (When you load a main chunk, 2012 If the <tt>allow_expression</tt> parameter is <tt>true</tt> then the entire text can be nothing more than an expression in which case the chunk returns the value of this expression.
2012 the resulting function will always have exactly one upvalue, 2013
2013 the <code>_ENV</code> variable (see <a href="#2.2">&sect;2.2</a>). 2014
2014 However, 2015 <h4 margin-top="1em"><a name="Luan.load_file"><tt>Luan.load_file (file_uri [, add_extension])</tt></a></h4>
2015 when you load a binary chunk created from a function (see <a href="#pdf-string.dump"><code>string.dump</code></a>), 2016
2016 the resulting function can have an arbitrary number of upvalues.) 2017 <p>
2017 All upvalues are fresh, that is, 2018 Similar to <a href="#Luan.load"><tt>load</tt></a>,
2018 they are not shared with any other function. 2019 but gets the chunk from file <tt>file_uri</tt>
2019
2020
2021 <p>
2022 <code>chunkname</code> is used as the name of the chunk for error messages
2023 and debug information (see <a href="#4.9">&sect;4.9</a>).
2024 When absent,
2025 it defaults to <code>chunk</code>, if <code>chunk</code> is a string,
2026 or to "<code>=(load)</code>" otherwise.
2027
2028
2029 <p>
2030 The string <code>mode</code> controls whether the chunk can be text or binary
2031 (that is, a precompiled chunk).
2032 It may be the string "<code>b</code>" (only binary chunks),
2033 "<code>t</code>" (only text chunks),
2034 or "<code>bt</code>" (both binary and text).
2035 The default is "<code>bt</code>".
2036
2037
2038 <p>
2039 Lua does not check the consistency of binary chunks.
2040 Maliciously crafted binary chunks can crash
2041 the interpreter.
2042
2043
2044
2045
2046 <p>
2047 <hr><h3><a name="pdf-loadfile"><code>loadfile ([filename [, mode [, env]]])</code></a></h3>
2048
2049
2050 <p>
2051 Similar to <a href="#pdf-load"><code>load</code></a>,
2052 but gets the chunk from file <code>filename</code>
2053 or from the standard input, 2020 or from the standard input,
2054 if no file name is given. 2021 if no file uri is given.
2055 2022
2056 2023 <p>
2057 2024 Could be defined as:
2058 2025
2059 <p> 2026 <p><tt><pre>
2060 <hr><h3><a name="pdf-next"><code>next (table [, index])</code></a></h3> 2027 function Luan.load_file(file_uri,add_extension)
2061 2028 file_uri = file_uri or "stdin:"
2062 2029 local f = Io.uri(file_uri,add_extension)
2063 <p> 2030 f.exists() or <a href="#Luan.error">Luan.error</a>("file '"..file_uri.."' not found")
2064 Allows a program to traverse all fields of a table. 2031 return <a href="#Luan.load">Luan.load</a>( f.read_text(), file_uri )
2065 Its first argument is a table and its second argument 2032 end
2066 is an index in this table. 2033 </pre></tt></p>
2067 <code>next</code> returns the next index of the table
2068 and its associated value.
2069 When called with <b>nil</b> as its second argument,
2070 <code>next</code> returns an initial index
2071 and its associated value.
2072 When called with the last index,
2073 or with <b>nil</b> in an empty table,
2074 <code>next</code> returns <b>nil</b>.
2075 If the second argument is absent, then it is interpreted as <b>nil</b>.
2076 In particular,
2077 you can use <code>next(t)</code> to check whether a table is empty.
2078
2079
2080 <p>
2081 The order in which the indices are enumerated is not specified,
2082 <em>even for numeric indices</em>.
2083 (To traverse a table in numeric order,
2084 use a numerical <b>for</b>.)
2085
2086
2087 <p>
2088 The behavior of <code>next</code> is undefined if,
2089 during the traversal,
2090 you assign any value to a non-existent field in the table.
2091 You may however modify existing fields.
2092 In particular, you may clear existing fields.
2093 2034
2094 2035
2095 2036
2096 2037
2097 <p> 2038 <p>