chacha/OpenRA
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
Files
fcb7d2a2adfff94de31bb831b237c0b86bcd5f19
OpenRA/lualibs/metalua/gg.lua

757 lines
29 KiB
Lua
Raw Blame History

----------------------------------------------------------------------
-- Metalua.
--
-- Summary: parser generator. Collection of higher order functors,
-- which allow to build and combine parsers. Relies on a lexer
-- that supports the same API as the one exposed in mll.lua.
--
----------------------------------------------------------------------
--
-- Copyright (c) 2006-2008, Fabien Fleutot <metalua@gmail.com>.
--
-- This software is released under the MIT Licence, see licence.txt
-- for details.
--
----------------------------------------------------------------------
--------------------------------------------------------------------------------
--
-- Exported API:
--
-- Parser generators:
-- * [gg.sequence()]
-- * [gg.multisequence()]
-- * [gg.expr()]
-- * [gg.list()]
-- * [gg.onkeyword()]
-- * [gg.optkeyword()]
--
-- Other functions:
-- * [gg.parse_error()]
-- * [gg.make_parser()]
-- * [gg.is_parser()]
--
--------------------------------------------------------------------------------
module("gg", package.seeall)
-------------------------------------------------------------------------------
-- parser metatable, which maps __call to method parse, and adds some
-- error tracing boilerplate.
-------------------------------------------------------------------------------
local parser_metatable = { }
function parser_metatable.__call (parser, lx, ...)
--printf ("Call parser %q of type %q", parser.name or "?", parser.kind)
if mlc.metabugs then
return parser:parse (lx, ...)
--local x = parser:parse (lx, ...)
--printf ("Result of parser %q: %s",
-- parser.name or "?",
-- _G.table.tostring(x, "nohash", 80))
--return x
else
local li = lx:lineinfo_right() or { "?", "?", "?", "?" }
local status, ast = pcall (parser.parse, parser, lx, ...)
if status then return ast else
-- Try to replace the gg.lua location, in the error msg, with
-- the place where the current parser started handling the
-- lexstream.
-- Since the error is rethrown, these places are stacked.
error (string.format ("%s\n - (l.%s, c.%s, k.%s) in parser %s",
ast:match "gg.lua:%d+: (.*)" or ast,
li[1], li[2], li[3], parser.name or parser.kind))
end
end
end
-------------------------------------------------------------------------------
-- Turn a table into a parser, mainly by setting the metatable.
-------------------------------------------------------------------------------
function make_parser(kind, p)
p.kind = kind
if not p.transformers then p.transformers = { } end
function p.transformers:add (x)
table.insert (self, x)
end
setmetatable (p, parser_metatable)
return p
end
-------------------------------------------------------------------------------
-- Return true iff [x] is a parser.
-- If it's a gg-generated parser, return the name of its kind.
-------------------------------------------------------------------------------
function is_parser (x)
return type(x)=="function" or getmetatable(x)==parser_metatable and x.kind
end
-------------------------------------------------------------------------------
-- Parse a sequence, without applying builder nor transformers
-------------------------------------------------------------------------------
local function raw_parse_sequence (lx, p)
local r = { }
for i=1, #p do
e=p[i]
if type(e) == "string" then
if not lx:is_keyword (lx:next(), e) then
parse_error (lx, "A keyword was expected, probably `%s'.", e) end
elseif is_parser (e) then
table.insert (r, e (lx))
else
gg.parse_error (lx,"Sequence `%s': element #%i is neither a string "..
"nor a parser: %s",
p.name, i, table.tostring(e))
end
end
return r
end
-------------------------------------------------------------------------------
-- Parse a multisequence, without applying multisequence transformers.
-- The sequences are completely parsed.
-------------------------------------------------------------------------------
local function raw_parse_multisequence (lx, sequence_table, default)
local seq_parser = sequence_table[lx:is_keyword(lx:peek())]
if seq_parser then return seq_parser (lx)
elseif default then return default (lx)
else return false end
end
-------------------------------------------------------------------------------
-- Applies all transformers listed in parser on ast.
-------------------------------------------------------------------------------
local function transform (ast, parser, fli, lli)
if parser.transformers then
for _, t in ipairs (parser.transformers) do ast = t(ast) or ast end
end
if type(ast) == 'table'then
local ali = ast.lineinfo
if not ali or ali.first~=fli or ali.last~=lli then
ast.lineinfo = { first = fli, last = lli }
end
end
return ast
end
-------------------------------------------------------------------------------
-- Generate a tracable parsing error (not implemented yet)
-------------------------------------------------------------------------------
function parse_error(lx, fmt, ...)
local li = lx:lineinfo_left() or {-1,-1,-1, "<unknown file>"}
local msg = string.format("line %i, char %i: "..fmt, li[1], li[2], ...)
local src = lx.src
if li[3]>0 and src then
local i, j = li[3], li[3]
while src:sub(i,i) ~= '\n' and i>=0 do i=i-1 end
while src:sub(j,j) ~= '\n' and j<=#src do j=j+1 end
local srcline = src:sub (i+1, j-1)
local idx = string.rep (" ", li[2]).."^"
msg = string.format("%s\n>>> %s\n>>> %s", msg, srcline, idx)
end
error(msg)
end
-------------------------------------------------------------------------------
--
-- Sequence parser generator
--
-------------------------------------------------------------------------------
-- Input fields:
--
-- * [builder]: how to build an AST out of sequence parts. let [x] be the list
-- of subparser results (keywords are simply omitted). [builder] can be:
-- - [nil], in which case the result of parsing is simply [x]
-- - a string, which is then put as a tag on [x]
-- - a function, which takes [x] as a parameter and returns an AST.
--
-- * [name]: the name of the parser. Used for debug messages
--
-- * [transformers]: a list of AST->AST functions, applied in order on ASTs
-- returned by the parser.
--
-- * Table-part entries corresponds to keywords (strings) and subparsers
-- (function and callable objects).
--
-- After creation, the following fields are added:
-- * [parse] the parsing function lexer->AST
-- * [kind] == "sequence"
-- * [name] is set, if it wasn't in the input.
--
-------------------------------------------------------------------------------
function sequence (p)
make_parser ("sequence", p)
-------------------------------------------------------------------
-- Parsing method
-------------------------------------------------------------------
function p:parse (lx)
-- Raw parsing:
local fli = lx:lineinfo_right()
local seq = raw_parse_sequence (lx, self)
local lli = lx:lineinfo_left()
-- Builder application:
local builder, tb = self.builder, type (self.builder)
if tb == "string" then seq.tag = builder
elseif tb == "function" or builder and builder.__call then seq = builder(seq)
elseif builder == nil then -- nothing
else error ("Invalid builder of type "..tb.." in sequence") end
seq = transform (seq, self, fli, lli)
assert (not seq or seq.lineinfo)
return seq
end
-------------------------------------------------------------------
-- Construction
-------------------------------------------------------------------
-- Try to build a proper name
if p.name then
-- don't touch existing name
elseif type(p[1])=="string" then -- find name based on 1st keyword
if #p==1 then p.name=p[1]
elseif type(p[#p])=="string" then
p.name = p[1] .. " ... " .. p[#p]
else p.name = p[1] .. " ..." end
else -- can't find a decent name
p.name = "<anonymous>"
end
return p
end --</sequence>
-------------------------------------------------------------------------------
--
-- Multiple, keyword-driven, sequence parser generator
--
-------------------------------------------------------------------------------
-- in [p], useful fields are:
--
-- * [transformers]: as usual
--
-- * [name]: as usual
--
-- * Table-part entries must be sequence parsers, or tables which can
-- be turned into a sequence parser by [gg.sequence]. These
-- sequences must start with a keyword, and this initial keyword
-- must be different for each sequence. The table-part entries will
-- be removed after [gg.multisequence] returns.
--
-- * [default]: the parser to run if the next keyword in the lexer is
-- none of the registered initial keywords. If there's no default
-- parser and no suitable initial keyword, the multisequence parser
-- simply returns [false].
--
-- After creation, the following fields are added:
--
-- * [parse] the parsing function lexer->AST
--
-- * [sequences] the table of sequences, indexed by initial keywords.
--
-- * [add] method takes a sequence parser or a config table for
-- [gg.sequence], and adds/replaces the corresponding sequence
-- parser. If the keyword was already used, the former sequence is
-- removed and a warning is issued.
--
-- * [get] method returns a sequence by its initial keyword
--
-- * [kind] == "multisequence"
--
-------------------------------------------------------------------------------
function multisequence (p)
make_parser ("multisequence", p)
-------------------------------------------------------------------
-- Add a sequence (might be just a config table for [gg.sequence])
-------------------------------------------------------------------
function p:add (s)
-- compile if necessary:
local keyword = type(s)=='table' and s[1]
if type(s)=='table' and not is_parser(s) then sequence(s) end
if is_parser(s)~='sequence' or type(keyword)~='string' then
if self.default then -- two defaults
error ("In a multisequence parser, all but one sequences "..
"must start with a keyword")
else self.default = s end -- first default
elseif self.sequences[keyword] then -- duplicate keyword
eprintf (" *** Warning: keyword %q overloaded in multisequence ***",
keyword)
self.sequences[keyword] = s
else -- newly caught keyword
self.sequences[keyword] = s
end
end -- </multisequence.add>
-------------------------------------------------------------------
-- Get the sequence starting with this keyword. [kw :: string]
-------------------------------------------------------------------
function p:get (kw) return self.sequences [kw] end
-------------------------------------------------------------------
-- Remove the sequence starting with keyword [kw :: string]
-------------------------------------------------------------------
function p:del (kw)
if not self.sequences[kw] then
eprintf("*** Warning: trying to delete sequence starting "..
"with %q from a multisequence having no such "..
"entry ***", kw) end
local removed = self.sequences[kw]
self.sequences[kw] = nil
return removed
end
-------------------------------------------------------------------
-- Parsing method
-------------------------------------------------------------------
function p:parse (lx)
local fli = lx:lineinfo_right()
local x = raw_parse_multisequence (lx, self.sequences, self.default)
local lli = lx:lineinfo_left()
return transform (x, self, fli, lli)
end
-------------------------------------------------------------------
-- Construction
-------------------------------------------------------------------
-- Register the sequences passed to the constructor. They're going
-- from the array part of the parser to the hash part of field
-- [sequences]
p.sequences = { }
for i=1, #p do p:add (p[i]); p[i] = nil end
-- FIXME: why is this commented out?
--if p.default and not is_parser(p.default) then sequence(p.default) end
return p
end --</multisequence>
-------------------------------------------------------------------------------
--
-- Expression parser generator
--
-------------------------------------------------------------------------------
--
-- Expression configuration relies on three tables: [prefix], [infix]
-- and [suffix]. Moreover, the primary parser can be replaced by a
-- table: in this case the [primary] table will be passed to
-- [gg.multisequence] to create a parser.
--
-- Each of these tables is a modified multisequence parser: the
-- differences with respect to regular multisequence config tables are:
--
-- * the builder takes specific parameters:
-- - for [prefix], it takes the result of the prefix sequence parser,
-- and the prefixed expression
-- - for [infix], it takes the left-hand-side expression, the results
-- of the infix sequence parser, and the right-hand-side expression.
-- - for [suffix], it takes the suffixed expression, and theresult
-- of the suffix sequence parser.
--
-- * the default field is a list, with parameters:
-- - [parser] the raw parsing function
-- - [transformers], as usual
-- - [prec], the operator's precedence
-- - [assoc] for [infix] table, the operator's associativity, which
-- can be "left", "right" or "flat" (default to left)
--
-- In [p], useful fields are:
-- * [transformers]: as usual
-- * [name]: as usual
-- * [primary]: the atomic expression parser, or a multisequence config
-- table (mandatory)
-- * [prefix]: prefix operators config table, see above.
-- * [infix]: infix operators config table, see above.
-- * [suffix]: suffix operators config table, see above.
--
-- After creation, these fields are added:
-- * [kind] == "expr"
-- * [parse] as usual
-- * each table is turned into a multisequence, and therefore has an
-- [add] method
--
-------------------------------------------------------------------------------
function expr (p)
make_parser ("expr", p)
-------------------------------------------------------------------
-- parser method.
-- In addition to the lexer, it takes an optional precedence:
-- it won't read expressions whose precedence is lower or equal
-- to [prec].
-------------------------------------------------------------------
function p:parse (lx, prec)
prec = prec or 0
------------------------------------------------------
-- Extract the right parser and the corresponding
-- options table, for (pre|in|suff)fix operators.
-- Options include prec, assoc, transformers.
------------------------------------------------------
local function get_parser_info (tab)
local p2 = tab:get (lx:is_keyword (lx:peek()))
if p2 then -- keyword-based sequence found
local function parser(lx) return raw_parse_sequence(lx, p2) end
return parser, p2
else -- Got to use the default parser
local d = tab.default
if d then return d.parse or d.parser, d
else return false, false end
end
end
------------------------------------------------------
-- Look for a prefix sequence. Multiple prefixes are
-- handled through the recursive [p.parse] call.
-- Notice the double-transform: one for the primary
-- expr, and one for the one with the prefix op.
------------------------------------------------------
local function handle_prefix ()
local fli = lx:lineinfo_right()
local p2_func, p2 = get_parser_info (self.prefix)
local op = p2_func and p2_func (lx)
if op then -- Keyword-based sequence found
local ili = lx:lineinfo_right() -- Intermediate LineInfo
local e = p2.builder (op, self:parse (lx, p2.prec))
local lli = lx:lineinfo_left()
return transform (transform (e, p2, ili, lli), self, fli, lli)
else -- No prefix found, get a primary expression
local e = self.primary(lx)
local lli = lx:lineinfo_left()
return transform (e, self, fli, lli)
end
end --</expr.parse.handle_prefix>
------------------------------------------------------
-- Look for an infix sequence+right-hand-side operand.
-- Return the whole binary expression result,
-- or false if no operator was found.
------------------------------------------------------
local function handle_infix (e)
local p2_func, p2 = get_parser_info (self.infix)
if not p2 then return false end
-----------------------------------------
-- Handle flattening operators: gather all operands
-- of the series in [list]; when a different operator
-- is found, stop, build from [list], [transform] and
-- return.
-----------------------------------------
if (not p2.prec or p2.prec>prec) and p2.assoc=="flat" then
local fli = lx:lineinfo_right()
local pflat, list = p2, { e }
repeat
local op = p2_func(lx)
if not op then break end
table.insert (list, self:parse (lx, p2.prec))
local _ -- We only care about checking that p2==pflat
_, p2 = get_parser_info (self.infix)
until p2 ~= pflat
local e2 = pflat.builder (list)
local lli = lx:lineinfo_left()
return transform (transform (e2, pflat, fli, lli), self, fli, lli)
-----------------------------------------
-- Handle regular infix operators: [e] the LHS is known,
-- just gather the operator and [e2] the RHS.
-- Result goes in [e3].
-----------------------------------------
elseif p2.prec and p2.prec>prec or
p2.prec==prec and p2.assoc=="right" then
local fli = e.lineinfo.first -- lx:lineinfo_right()
local op = p2_func(lx)
if not op then return false end
local e2 = self:parse (lx, p2.prec)
local e3 = p2.builder (e, op, e2)
local lli = lx:lineinfo_left()
return transform (transform (e3, p2, fli, lli), self, fli, lli)
-----------------------------------------
-- Check for non-associative operators, and complain if applicable.
-----------------------------------------
elseif p2.assoc=="none" and p2.prec==prec then
parse_error (lx, "non-associative operator!")
-----------------------------------------
-- No infix operator suitable at that precedence
-----------------------------------------
else return false end
end --</expr.parse.handle_infix>
------------------------------------------------------
-- Look for a suffix sequence.
-- Return the result of suffix operator on [e],
-- or false if no operator was found.
------------------------------------------------------
local function handle_suffix (e)
-- FIXME bad fli, must take e.lineinfo.first
local p2_func, p2 = get_parser_info (self.suffix)
if not p2 then return false end
if not p2.prec or p2.prec>=prec then
--local fli = lx:lineinfo_right()
local fli = e.lineinfo.first
local op = p2_func(lx)
if not op then return false end
local lli = lx:lineinfo_left()
e = p2.builder (e, op)
e = transform (transform (e, p2, fli, lli), self, fli, lli)
return e
end
return false
end --</expr.parse.handle_suffix>
------------------------------------------------------
-- Parser body: read suffix and (infix+operand)
-- extensions as long as we're able to fetch more at
-- this precedence level.
------------------------------------------------------
local e = handle_prefix()
repeat
local x = handle_suffix (e); e = x or e
local y = handle_infix (e); e = y or e
until not (x or y)
-- No transform: it already happened in operators handling
return e
end --</expr.parse>
-------------------------------------------------------------------
-- Construction
-------------------------------------------------------------------
if not p.primary then p.primary=p[1]; p[1]=nil end
for _, t in ipairs{ "primary", "prefix", "infix", "suffix" } do
if not p[t] then p[t] = { } end
if not is_parser(p[t]) then multisequence(p[t]) end
end
function p:add(...) return self.primary:add(...) end
return p
end --</expr>
-------------------------------------------------------------------------------
--
-- List parser generator
--
-------------------------------------------------------------------------------
-- In [p], the following fields can be provided in input:
--
-- * [builder]: takes list of subparser results, returns AST
-- * [transformers]: as usual
-- * [name]: as usual
--
-- * [terminators]: list of strings representing the keywords which
-- might mark the end of the list. When non-empty, the list is
-- allowed to be empty. A string is treated as a single-element
-- table, whose element is that string, e.g. ["do"] is the same as
-- [{"do"}].
--
-- * [separators]: list of strings representing the keywords which can
-- separate elements of the list. When non-empty, one of these
-- keyword has to be found between each element. Lack of a separator
-- indicates the end of the list. A string is treated as a
-- single-element table, whose element is that string, e.g. ["do"]
-- is the same as [{"do"}]. If [terminators] is empty/nil, then
-- [separators] has to be non-empty.
--
-- After creation, the following fields are added:
-- * [parse] the parsing function lexer->AST
-- * [kind] == "list"
--
-------------------------------------------------------------------------------
function list (p)
make_parser ("list", p)
-------------------------------------------------------------------
-- Parsing method
-------------------------------------------------------------------
function p:parse (lx)
------------------------------------------------------
-- Used to quickly check whether there's a terminator
-- or a separator immediately ahead
------------------------------------------------------
local function peek_is_in (keywords)
return keywords and lx:is_keyword(lx:peek(), unpack(keywords)) end
local x = { }
local fli = lx:lineinfo_right()
-- if there's a terminator to start with, don't bother trying
if not peek_is_in (self.terminators) then
repeat table.insert (x, self.primary (lx)) -- read one element
until
-- First reason to stop: There's a separator list specified,
-- and next token isn't one. Otherwise, consume it with [lx:next()]
self.separators and not(peek_is_in (self.separators) and lx:next()) or
-- Other reason to stop: terminator token ahead
peek_is_in (self.terminators) or
-- Last reason: end of file reached
lx:peek().tag=="Eof"
end
local lli = lx:lineinfo_left()
-- Apply the builder. It can be a string, or a callable value,
-- or simply nothing.
local b = self.builder
if b then
if type(b)=="string" then x.tag = b -- b is a string, use it as a tag
elseif type(b)=="function" then x=b(x)
else
local bmt = getmetatable(b)
if bmt and bmt.__call then x=b(x) end
end
end
return transform (x, self, fli, lli)
end --</list.parse>
-------------------------------------------------------------------
-- Construction
-------------------------------------------------------------------
if not p.primary then p.primary = p[1]; p[1] = nil end
if type(p.terminators) == "string" then p.terminators = { p.terminators }
elseif p.terminators and #p.terminators == 0 then p.terminators = nil end
if type(p.separators) == "string" then p.separators = { p.separators }
elseif p.separators and #p.separators == 0 then p.separators = nil end
return p
end --</list>
-------------------------------------------------------------------------------
--
-- Keyword-conditionned parser generator
--
-------------------------------------------------------------------------------
--
-- Only apply a parser if a given keyword is found. The result of
-- [gg.onkeyword] parser is the result of the subparser (modulo
-- [transformers] applications).
--
-- lineinfo: the keyword is *not* included in the boundaries of the
-- resulting lineinfo. A review of all usages of gg.onkeyword() in the
-- implementation of metalua has shown that it was the appropriate choice
-- in every case.
--
-- Input fields:
--
-- * [name]: as usual
--
-- * [transformers]: as usual
--
-- * [peek]: if non-nil, the conditionning keyword is left in the lexeme
-- stream instead of being consumed.
--
-- * [primary]: the subparser.
--
-- * [keywords]: list of strings representing triggering keywords.
--
-- * Table-part entries can contain strings, and/or exactly one parser.
-- Strings are put in [keywords], and the parser is put in [primary].
--
-- After the call, the following fields will be set:
--
-- * [parse] the parsing method
-- * [kind] == "onkeyword"
-- * [primary]
-- * [keywords]
--
-------------------------------------------------------------------------------
function onkeyword (p)
make_parser ("onkeyword", p)
-------------------------------------------------------------------
-- Parsing method
-------------------------------------------------------------------
function p:parse(lx)
if lx:is_keyword (lx:peek(), unpack(self.keywords)) then
--local fli = lx:lineinfo_right()
if not self.peek then lx:next() end
local content = self.primary (lx)
--local lli = lx:lineinfo_left()
local fli, lli = content.lineinfo.first, content.lineinfo.last
return transform (content, p, fli, lli)
else return false end
end
-------------------------------------------------------------------
-- Construction
-------------------------------------------------------------------
if not p.keywords then p.keywords = { } end
for _, x in ipairs(p) do
if type(x)=="string" then table.insert (p.keywords, x)
else assert (not p.primary and is_parser (x)); p.primary = x end
end
if not next (p.keywords) then
eprintf("Warning, no keyword to trigger gg.onkeyword") end
assert (p.primary, 'no primary parser in gg.onkeyword')
return p
end --</onkeyword>
-------------------------------------------------------------------------------
--
-- Optional keyword consummer pseudo-parser generator
--
-------------------------------------------------------------------------------
--
-- This doesn't return a real parser, just a function. That function parses
-- one of the keywords passed as parameters, and returns it. It returns
-- [false] if no matching keyword is found.
--
-- Notice that tokens returned by lexer already carry lineinfo, therefore
-- there's no need to add them, as done usually through transform() calls.
-------------------------------------------------------------------------------
function optkeyword (...)
local args = {...}
if type (args[1]) == "table" then
assert (#args == 1)
args = args[1]
end
for _, v in ipairs(args) do assert (type(v)=="string") end
return function (lx)
local x = lx:is_keyword (lx:peek(), unpack (args))
if x then lx:next(); return x
else return false end
end
end
-------------------------------------------------------------------------------
--
-- Run a parser with a special lexer
--
-------------------------------------------------------------------------------
--
-- This doesn't return a real parser, just a function.
-- First argument is the lexer class to be used with the parser,
-- 2nd is the parser itself.
-- The resulting parser returns whatever the argument parser does.
--
-------------------------------------------------------------------------------
function with_lexer(new_lexer, parser)
-------------------------------------------------------------------
-- Most gg functions take their parameters in a table, so it's
-- better to silently accept when with_lexer{ } is called with
-- its arguments in a list:
-------------------------------------------------------------------
if not parser and #new_lexer==2 and type(new_lexer[1])=='table' then
return with_lexer(unpack(new_lexer))
end
-------------------------------------------------------------------
-- Save the current lexer, switch it for the new one, run the parser,
-- restore the previous lexer, even if the parser caused an error.
-------------------------------------------------------------------
return function (lx)
local old_lexer = getmetatable(lx)
lx:sync()
setmetatable(lx, new_lexer)
local status, result = pcall(parser, lx)
lx:sync()
setmetatable(lx, old_lexer)
if status then return result else error(result) end
end
end
Reference in New Issue View Git Blame Copy Permalink