31 lines
715 B
Lua
31 lines
715 B
Lua
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local re = require 'relabel'
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local g = re.compile[[
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S <- Id List
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List <- !. / Comma Id List
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Id <- Sp [a-z]+ / %{2}
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Comma <- Sp ',' / %{3}
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Sp <- %s*
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]]
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function mymatch (g, s)
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local r, e, sfail = g:match(s)
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if not r then
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local line, col = re.calcline(s, #s - #sfail)
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local msg = "Error at line " .. line .. " (col " .. col .. ")"
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if e == 1 then
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return r, msg .. ": expecting an identifier before '" .. sfail .. "'"
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elseif e == 2 then
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return r, msg .. ": expecting ',' before '" .. sfail .. "'"
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else
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return r, msg
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end
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end
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return r
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end
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print(mymatch(g, "one,two"))
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print(mymatch(g, "one two"))
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print(mymatch(g, "one,\n two,\nthree,"))
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