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100 lines
2.9 KiB
Lua
100 lines
2.9 KiB
Lua
--- Common functions for strings.
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--
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-- @module gear.strings
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-- @copyright 2022 The DoubleFourteen Code Forge
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-- @author Lorenzo Cogotti
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local strings = {}
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-- Platform preferred path separator
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local SEP = package.config:sub(1,1)
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--- Remove redundant slashes and resolve dot and dot-dots in path.
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--
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-- @string path a file path
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-- @string[opt] sep separator pattern, '/' for Unix, '\\' for Windows (default)
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-- @string[optchain] osep target separator pattern, '/' for Unix, '\\' for Windows, uses the platform preferred path separator by default.
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-- @treturn string cleared path
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function strings.clearpath(path, sep, osep)
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sep = sep or '\\' -- conservative, both / and \ as seps
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osep = osep or SEP
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local dot, dotdot, sepsub, esub
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if sep == '\\' then
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-- Windows style separator pattern
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dot, dotdot = '[\\/]+%.?[\\/]', '[^\\/]+[\\/]%.%.[\\/]?'
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sepsub, esub = '[\\/]', '[\\/]$'
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elseif sep == '/' then
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-- Unix like separators only
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dot, dotdot = '/+%.?/', '[^/]+/%.%./?'
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sepsub, esub = '/', '/$'
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else
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error("Unsupported separator pattern: "..tostring(sep))
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end
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if osep ~= '\\' and osep ~= '/' then
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error("Unsupported target separator pattern: "..tostring(osep))
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end
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local k
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repeat -- /./ -> /
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path,k = path:gsub(dot, osep, 1)
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until k == 0
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repeat -- A/../ -> (empty)
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path,k = path:gsub(dotdot, '', 1)
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until k == 0
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-- Make separators consistent
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path = path:gsub(sepsub, osep)
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path = path:gsub(esub, '') -- never leave trailing separator
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return path == '' and '.' or path
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end
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--- Split path into components: directory, basename, extension.
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--
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-- @string path path to be split
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-- @treturn string directory name (including separator), '' if none was found in path
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-- @treturn string file name without extension, '' if none was found in path
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-- @treturn string file extension including '.', '' if none was found in path
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function strings.splitpath(path)
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return path:match("(.-)([^\\/]-)(%.?[^%.\\/]*)$")
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end
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--- Test whether a string starts with a prefix.
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--
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-- This is an optimized version of: return s:sub(1, #prefix) == prefix.
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--
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-- @string s string to be tested
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-- @string prefix prefix to test for
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-- @treturn bool true if prefix is found, false otherwise
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function strings.startswith(s, prefix)
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for i = 1,#prefix do
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if s:byte(i) ~= prefix:byte(i) then
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return false
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end
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end
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return true
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end
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--- Test whether a string ends with a trailing suffix.
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--
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-- This is an optimized version of: return trailing == ""
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-- or s:sub(-#trailing) == trailing.
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--
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-- @string s string to be tested
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-- @string trailing suffix to test for
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-- @treturn bool true if suffix is found, false otherwise
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function strings.endswith(s, trailing)
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local n1,n2 = #s,#trailing
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for i = 0,n2-1 do
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if s:byte(n1-i) ~= trailing:byte(n2-i) then
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return false
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end
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end
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return true
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end
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return strings
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