64 lines
2.0 KiB
Plaintext
64 lines
2.0 KiB
Plaintext
-- This file contains the parser, which converts text into abstract syntax trees
|
|
lpeg = require 'lpeg'
|
|
re = require 're'
|
|
lpeg.setmaxstack 20000
|
|
{:P,:R,:S,:C,:Cmt,:Carg,:Cc} = lpeg
|
|
|
|
DEFS = with {}
|
|
-- Newline supports either windows-style CR+LF or unix-style LF
|
|
.nl = P("\r")^-1 * P("\n")
|
|
.tab = P("\t")
|
|
.tonumber = tonumber
|
|
.tochar = string.char
|
|
.unpack = unpack or table.unpack
|
|
.nil = Cc(nil)
|
|
.userdata = Carg(1)
|
|
.utf8_char = (
|
|
R("\194\223")*R("\128\191") +
|
|
R("\224\239")*R("\128\191")*R("\128\191") +
|
|
R("\240\244")*R("\128\191")*R("\128\191")*R("\128\191"))
|
|
.Tree = (t, userdata)-> userdata.make_tree(t, userdata)
|
|
|
|
setmetatable(DEFS, {__index:(key)=>
|
|
if i = key\match("^ascii_(%d+)$")
|
|
c = string.char(tonumber(i))
|
|
self[key] = c
|
|
return c
|
|
elseif i = key\match("^number_(%d+)$")
|
|
p = Cc(tonumber(i))
|
|
self[key] = p
|
|
return p
|
|
})
|
|
|
|
-- Just for cleanliness, I put the language spec in its own file using a slightly modified
|
|
-- version of the lpeg.re syntax.
|
|
peg_tidier = re.compile [[
|
|
file <- %nl* {~ (def/comment) (%nl+ (def/comment))* %nl* ~}
|
|
def <- anon_def / captured_def
|
|
anon_def <-
|
|
({ident} (" "*) ":" {[^%nl]* (%nl+ " "+ [^%nl]*)*})
|
|
-> "%1 <- %2"
|
|
captured_def <-
|
|
({ident} (" "*) "(" {ident} ")" (" "*) ":" {[^%nl]* (%nl+ " "+ [^%nl]*)*})
|
|
-> "%1 <- ({| {:start:{}:} %3 {:stop:{}:} {:type: (''->'%2') :} |} %%userdata) -> Tree"
|
|
ident <- [a-zA-Z_][a-zA-Z0-9_]*
|
|
comment <- "--" [^%nl]*
|
|
]]
|
|
|
|
make_parser = (peg, make_tree=nil)->
|
|
peg = assert(peg_tidier\match(peg))
|
|
peg = assert(re.compile(peg, DEFS))
|
|
return (input, filename='???')->
|
|
input = tostring(input)
|
|
tree_mt = {__index: {source:input, filename:filename}}
|
|
userdata = {
|
|
make_tree: make_tree or ((t)->setmetatable(t, tree_mt))
|
|
:filename, source:input
|
|
}
|
|
tree = peg\match(input, nil, userdata)
|
|
if not tree
|
|
error "File #{filename} failed to parse:\n#{input}"
|
|
return tree
|
|
|
|
return make_parser
|