Bruce Hill
b6d3cbd61c
relative to the text, not the opening '("', code objects can now remove
all free vars, the REPL uses global vars. Error API is changing a bit.
82 lines
2.6 KiB
Plaintext
82 lines
2.6 KiB
Plaintext
-- This file contains the parser, which converts text into abstract syntax trees
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lpeg = require 'lpeg'
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re = require 're'
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lpeg.setmaxstack 20000
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{:P,:R,:S,:C,:Cmt,:Carg,:Cc} = lpeg
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-- foldr {A{a1,a2,...},B{b1,b2,...},C{c1,c2,...}} -> C{B{A{a1,a2,...},b1,b2...},c1,c2...}
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foldr = (...)->
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inner = select(1,...)
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for i=2,select('#',...) do
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assert inner.type
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outer = select(i,...)
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table.insert(outer, 1, inner)
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inner.start = outer.start
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inner = outer
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assert inner.type
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return inner
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DEFS = with {}
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-- Newline supports either windows-style CR+LF or unix-style LF
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.nl = P("\r")^-1 * P("\n")
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.tab = P("\t")
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.tonumber = tonumber
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.tochar = string.char
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.unpack = unpack or table.unpack
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.nil = Cc(nil)
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.userdata = Carg(1)
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-- Always match and capture the indentation (spaces only) of the current line
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-- i.e. the leading space of the chunk of non-newline characters leading up to s[i]
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.indentation = lpeg.Cmt P(0),
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(s, i)->
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sub = string.sub
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while i > 1 and sub(s,i-1,i-1) != '\n' do i -= 1
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return true, (s\match("^ *", i))
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.utf8_char = (
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R("\194\223")*R("\128\191") +
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R("\224\239")*R("\128\191")*R("\128\191") +
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R("\240\244")*R("\128\191")*R("\128\191")*R("\128\191"))
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.Tree = (t, userdata)-> userdata.make_tree(t, userdata)
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.foldr = foldr
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setmetatable(DEFS, {__index:(key)=>
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if i = key\match("^ascii_(%d+)$")
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c = string.char(tonumber(i))
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self[key] = c
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return c
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elseif i = key\match("^number_(%d+)$")
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p = Cc(tonumber(i))
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self[key] = p
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return p
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})
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-- Just for cleanliness, I put the language spec in its own file using a slightly
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-- extended version of the lpeg.re syntax.
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peg_tidier = re.compile [[
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file <- %nl* {~ (captured_def/line) (%nl+ (captured_def/line))* %nl* ~}
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ident <- [a-zA-Z_][a-zA-Z0-9_]*
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line <- [^%nl]*
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captured_def <-
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({ident} (" "*) "(" {ident} ")" (" "*) "<-" {[^%nl]* (%nl+ " "+ [^%nl]*)*}) ->
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"%1 <- ({| {:type:''->'%2':} {:start:{}:}
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(%3)
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{:stop:{}:} |} %%userdata) -> Tree"
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]]
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make_parser = (peg, make_tree=nil)->
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peg = assert(peg_tidier\match(peg))
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peg = assert(re.compile(peg, DEFS))
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return (input, filename='???')->
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input = tostring(input)
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tree_mt = {__index: {source:input, filename:filename}}
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userdata = {
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make_tree: make_tree or ((t)->setmetatable(t, tree_mt))
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:filename, source:input
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}
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tree = peg\match(input, nil, userdata)
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if not tree
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error "File #{filename} failed to parse:\n#{input}"
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return tree
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return make_parser
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