mirror of
https://github.com/notwa/lips
synced 2024-06-26 00:27:13 -07:00
91 lines
2.7 KiB
Lua
91 lines
2.7 KiB
Lua
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local insert = table.insert
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local Muncher = require "lips.Muncher"
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local Preproc = require("lips.Class")(Muncher)
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function Preproc:init(options)
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self.options = options or {}
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end
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function Preproc:process(tokens)
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self.tokens = tokens
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local defines = {}
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local plus_labels = {} -- constructed forwards
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local minus_labels = {} -- constructed backwards
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-- first pass: collect tokens, constants, and relative labels.
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self.i = 0
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while self.i < #self.tokens do
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local tt, tok = self:advance()
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if tt == 'DEF' then
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local tt2, tok2 = self:advance()
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if tt2 ~= 'NUM' then
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self:error('expected number for define')
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end
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defines[tok] = tok2
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elseif tt == 'RELLABEL' then
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if tok == '+' then
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insert(plus_labels, self.i)
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elseif tok == '-' then
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insert(minus_labels, 1, self.i)
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else
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error('Internal Error: unexpected token for relative label')
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end
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elseif tt == nil then
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error('Internal Error: missing token')
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end
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end
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-- resolve defines and relative labels
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for i, t in ipairs(self.tokens) do
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self.fn = t.fn
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self.line = t.line
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if t.tt == 'DEFSYM' then
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t.tt = 'NUM'
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t.tok = defines[t.tok]
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if t.tok == nil then
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self:error('undefined define') -- uhhh nice wording
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end
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elseif t.tt == 'RELLABEL' then
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t.tt = 'LABEL'
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-- exploits the fact that user labels can't begin with a number
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t.tok = tostring(i)
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elseif t.tt == 'RELLABELSYM' then
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t.tt = 'LABELSYM'
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local rel = t.tok
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local seen = 0
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-- TODO: don't iterate over *every* label, just the ones nearby
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if rel > 0 then
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for _, label_i in ipairs(plus_labels) do
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if label_i > i then
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seen = seen + 1
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if seen == rel then
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t.tok = tostring(label_i)
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break
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end
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end
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end
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else
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for _, label_i in ipairs(minus_labels) do
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if label_i < i then
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seen = seen - 1
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if seen == rel then
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t.tok = tostring(label_i)
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break
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end
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end
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end
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end
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if seen ~= rel then
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self:error('could not find appropriate relative label')
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end
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end
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end
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return self.tokens
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end
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return Preproc
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