org.classdump.luna.lib

Class StringLib

java.lang.Object

org.classdump.luna.lib.StringLib

public final class StringLib
extends Object

This library provides generic functions for string manipulation, such as finding and extracting substrings, and pattern matching. When indexing a string in Lua, the first character is at position 1 (not at 0, as in C). Indices are allowed to be negative and are interpreted as indexing backwards, from the end of the string. Thus, the last character is at position -1, and so on.

The string library provides all its functions inside the table string. It also sets a metatable for strings where the __index field points to the string table. Therefore, you can use the string functions in object-oriented style. For instance, string.byte(s,i) can be written as s:byte(i).

The string library assumes one-byte character encodings.

Method Summary

Modifier and Type	Method and Description
static org.classdump.luna.runtime.LuaFunction	byteFn() Returns the function string.byte.
static org.classdump.luna.runtime.LuaFunction	charFn() Returns the function string.char.
static org.classdump.luna.runtime.LuaFunction	dump() Returns the function string.dump.
static org.classdump.luna.runtime.LuaFunction	find() Returns the function string.find.
static org.classdump.luna.runtime.LuaFunction	format() Returns the function string.format.
static org.classdump.luna.runtime.LuaFunction	gmatch() Returns the function string.gmatch.
static org.classdump.luna.runtime.LuaFunction	gsub() Returns the function string.gsub.
static void	installInto(org.classdump.luna.StateContext context, org.classdump.luna.Table env) Installs the string library to the global environment env in the state context context.
static org.classdump.luna.runtime.LuaFunction	len() Returns the function string.len.
static org.classdump.luna.runtime.LuaFunction	lower() Returns the function string.lower.
static org.classdump.luna.runtime.LuaFunction	match() Returns the function string.match.
static org.classdump.luna.runtime.LuaFunction	rep() Returns the function string.rep.
static org.classdump.luna.runtime.LuaFunction	reverse() Returns the function string.reverse.
static org.classdump.luna.runtime.LuaFunction	sub() Returns the function string.sub.
static org.classdump.luna.runtime.LuaFunction	upper() Returns the function string.upper.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

byteFn

public static org.classdump.luna.runtime.LuaFunction byteFn()

Returns the function string.byte.

The following is the corresponding entry from the Lua Reference Manual:

string.byte (s [, i [, j]])

Returns the internal numeric codes of the characters s[i], s[i+1], ..., s[j]. The default value for i is 1; the default value for j is i. These indices are corrected following the same rules of function string.sub.

Numeric codes are not necessarily portable across platforms.

Returns:

the string.byte function

See Also:

the Lua 5.3 Reference Manual entry for string.byte

charFn

public static org.classdump.luna.runtime.LuaFunction charFn()

Returns the function string.char.

The following is the corresponding entry from the Lua Reference Manual:

string.char (···)

Receives zero or more integers. Returns a string with length equal to the number of arguments, in which each character has the internal numeric code equal to its corresponding argument.

Numeric codes are not necessarily portable across platforms.

Returns:

the string.char function

See Also:

the Lua 5.3 Reference Manual entry for string.char

dump

public static org.classdump.luna.runtime.LuaFunction dump()

Returns the function string.dump.

The following is the corresponding entry from the Lua Reference Manual:

string.dump (function [, strip])

Returns a string containing a binary representation (a binary chunk) of the given function, so that a later load on this string returns a copy of the function (but with new upvalues). If strip is a true value, the binary representation may not include all debug information about the function, to save space.

Functions with upvalues have only their number of upvalues saved. When (re)loaded, those upvalues receive fresh instances containing nil. (You can use the debug library to serialize and reload the upvalues of a function in a way adequate to your needs.)

Returns:

the string.dump function

See Also:

the Lua 5.3 Reference Manual entry for string.dump

find

public static org.classdump.luna.runtime.LuaFunction find()

Returns the function string.find.

The following is the corresponding entry from the Lua Reference Manual:

string.find (s, pattern [, init [, plain]])

Looks for the first match of pattern (see §6.4.1) in the string s. If it finds a match, then find returns the indices of s where this occurrence starts and ends; otherwise, it returns nil. A third, optional numeric argument init specifies where to start the search; its default value is 1 and can be negative. A value of true as a fourth, optional argument plain turns off the pattern matching facilities, so the function does a plain "find substring" operation, with no characters in pattern being considered magic. Note that if plain is given, then init must be given as well.

If the pattern has captures, then in a successful match the captured values are also returned, after the two indices.

Returns:

the string.find function

See Also:

the Lua 5.3 Reference Manual entry for string.find

format

public static org.classdump.luna.runtime.LuaFunction format()

Returns the function string.format.

The following is the corresponding entry from the Lua Reference Manual:

string.format (formatstring, ···)

Returns a formatted version of its variable number of arguments following the description given in its first argument (which must be a string). The format string follows the same rules as the ISO C function sprintf. The only differences are that the options/modifiers *, h, L, l, n, and p are not supported and that there is an extra option, q. The q option formats a string between double quotes, using escape sequences when necessary to ensure that it can safely be read back by the Lua interpreter. For instance, the call

 
 string.format('%q', 'a string with "quotes" and \n new line')
 
 

may produce the string:

 
 "a string with \"quotes\" and \
 new line"
 }
 

Options A, a, E, e, f, G, and g all expect a number as argument. Options c, d, i, o, u, X, and x expect an integer. Option q expects a string. Option s expects a string; if its argument is not a string, it is converted to one following the same rules of tostring. If the option has any modifier (flags, width, length), the string argument should not contain embedded zeros. When Lua is compiled with a non-C99 compiler, options A and a (hexadecimal floats) do not support any modifier (flags, width, length).

Returns:

the string.format function

See Also:

the Lua 5.3 Reference Manual entry for string.format

gmatch

public static org.classdump.luna.runtime.LuaFunction gmatch()

Returns the function string.gmatch.

The following is the corresponding entry from the Lua Reference Manual:

string.gmatch (s, pattern)

Returns an iterator function that, each time it is called, returns the next captures from pattern (see §6.4.1) over the string s. If pattern specifies no captures, then the whole match is produced in each call.

As an example, the following loop will iterate over all the words from string s, printing one per line:

 
 s = "hello world from Lua"
 for w in string.gmatch(s, "%a+") do
   print(w)
 end
 
 

The next example collects all pairs key=value from the given string into a table:

 
 t = {}
 s = "from=world, to=Lua"
 for k, v in string.gmatch(s, "(%w+)=(%w+)") do
   t[k] = v
 end
 
 

For this function, a caret '^' at the start of a pattern does not work as an anchor, as this would prevent the iteration.

Returns:

the string.gmatch function

See Also:

the Lua 5.3 Reference Manual entry for string.gmatch

gsub

public static org.classdump.luna.runtime.LuaFunction gsub()

Returns the function string.gsub.

The following is the corresponding entry from the Lua Reference Manual:

string.gsub (s, pattern, repl [, n])

Returns a copy of s in which all (or the first n, if given) occurrences of the pattern (see §6.4.1) have been replaced by a replacement string specified by repl, which can be a string, a table, or a function. gsub also returns, as its second value, the total number of matches that occurred. The name gsub comes from Global SUBstitution.

If repl is a string, then its value is used for replacement. The character % works as an escape character: any sequence in repl of the form %d, with d between 1 and 9, stands for the value of the d-th captured substring. The sequence %0 stands for the whole match. The sequence %% stands for a single %.

If repl is a table, then the table is queried for every match, using the first capture as the key.

If repl is a function, then this function is called every time a match occurs, with all captured substrings passed as arguments, in order.

In any case, if the pattern specifies no captures, then it behaves as if the whole pattern was inside a capture.

If the value returned by the table query or by the function call is a string or a number, then it is used as the replacement string; otherwise, if it is false or nil, then there is no replacement (that is, the original match is kept in the string).

Here are some examples:

 
 x = string.gsub("hello world", "(%w+)", "%1 %1")
 --> x="hello hello world world"
 
 

 
 x = string.gsub("hello world", "%w+", "%0 %0", 1)
 --> x="hello hello world"
 
 

 
 x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1")
 --> x="world hello Lua from"
 
 

 
 x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv)
 --> x="home = /home/roberto, user = roberto"
 
 

 
 x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s)
       return load(s)()
     end)
 --> x="4+5 = 9"
 
 

 
 local t = {name="lua", version="5.3"}
 x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t)
 --> x="lua-5.3.tar.gz"
 
 

Returns:

the string.gsub function

See Also:

the Lua 5.3 Reference Manual entry for string.gsub

len

public static org.classdump.luna.runtime.LuaFunction len()

Returns the function string.len.

The following is the corresponding entry from the Lua Reference Manual:

string.len (s)

Receives a string and returns its length. The empty string "" has length 0. Embedded zeros are counted, so "a\000bc\000" has length 5.

Returns:

the string.len function

See Also:

the Lua 5.3 Reference Manual entry for string.len

lower

public static org.classdump.luna.runtime.LuaFunction lower()

Returns the function string.lower.

The following is the corresponding entry from the Lua Reference Manual:

string.lower (s)

Receives a string and returns a copy of this string with all uppercase letters changed to lowercase. All other characters are left unchanged. The definition of what an uppercase letter is depends on the current locale.

Returns:

the string.lower function

See Also:

the Lua 5.3 Reference Manual entry for string.lower

match

public static org.classdump.luna.runtime.LuaFunction match()

Returns the function string.match.

The following is the corresponding entry from the Lua Reference Manual:

string.match (s, pattern [, init])

Looks for the first match of pattern (see §6.4.1) in the string s. If it finds one, then match returns the captures from the pattern; otherwise it returns nil. If pattern specifies no captures, then the whole match is returned. A third, optional numeric argument init specifies where to start the search; its default value is 1 and can be negative.

Returns:

the string.match function

See Also:

the Lua 5.3 Reference Manual entry for string.match

rep

public static org.classdump.luna.runtime.LuaFunction rep()

Returns the function string.rep.

The following is the corresponding entry from the Lua Reference Manual:

string.rep (s, n [, sep])

Returns a string that is the concatenation of n copies of the string s separated by the string sep. The default value for sep is the empty string (that is, no separator). Returns the empty string if n is not positive.

(Note that it is very easy to exhaust the memory of your machine with a single call to this function.)

Returns:

the string.rep function

See Also:

the Lua 5.3 Reference Manual entry for string.rep

reverse

public static org.classdump.luna.runtime.LuaFunction reverse()

Returns the function string.reverse.

The following is the corresponding entry from the Lua Reference Manual:

string.reverse (s)

Returns a string that is the string s reversed.

Returns:

the string.reverse function

See Also:

the Lua 5.3 Reference Manual entry for string.reverse

sub

public static org.classdump.luna.runtime.LuaFunction sub()

Returns the function string.sub.

The following is the corresponding entry from the Lua Reference Manual:

string.sub (s, i [, j])

Returns the substring of s that starts at i and continues until j; i and j can be negative. If j is absent, then it is assumed to be equal to -1 (which is the same as the string length). In particular, the call string.sub(s,1,j) returns a prefix of s with length j, and string.sub(s, -i) returns a suffix of s with length i.

If, after the translation of negative indices, i is less than 1, it is corrected to 1. If j is greater than the string length, it is corrected to that length. If, after these corrections, i is greater than j, the function returns the empty string.

Returns:

the string.sub function

See Also:

the Lua 5.3 Reference Manual entry for string.sub

upper

public static org.classdump.luna.runtime.LuaFunction upper()

Returns the function string.upper.

The following is the corresponding entry from the Lua Reference Manual:

string.upper (s)

Receives a string and returns a copy of this string with all lowercase letters changed to uppercase. All other characters are left unchanged. The definition of what a lowercase letter is depends on the current locale.

Returns:

the string.upper function

See Also:

the Lua 5.3 Reference Manual entry for string.upper

installInto

public static void installInto(org.classdump.luna.StateContext context,
                               org.classdump.luna.Table env)

Installs the string library to the global environment env in the state context context.

If env.package.loaded is a table, adds the library table to it with the key "string", using raw access.

Parameters:

context - the state context, must not be null

env - the global environment, must not be null

Throws:

NullPointerException - if context or env is null