--------------------------------------------------------------------------------
|
-- Copyright (c) 2006-2013 Fabien Fleutot and others.
|
--
|
-- All rights reserved.
|
--
|
-- This program and the accompanying materials are made available
|
-- under the terms of the Eclipse Public License v1.0 which
|
-- accompanies this distribution, and is available at
|
-- http://www.eclipse.org/legal/epl-v10.html
|
--
|
-- This program and the accompanying materials are also made available
|
-- under the terms of the MIT public license which accompanies this
|
-- distribution, and is available at http://www.lua.org/license.html
|
--
|
-- Contributors:
|
-- Fabien Fleutot - API and implementation
|
--
|
--------------------------------------------------------------------------------
|
|
--------------------------------------------------------------------------------
|
--
|
-- 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.
|
--
|
--------------------------------------------------------------------------------
|
|
--------------------------------------------------------------------------------
|
--
|
-- 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()]
|
--
|
--------------------------------------------------------------------------------
|
|
local M = { }
|
local unpack = table.unpack or unpack
|
|
local pp = require 'metalua.pprint'
|
local lexer = require 'metalua.grammar.lexer'
|
|
--------------------------------------------------------------------------------
|
-- Symbol generator: [gensym()] returns a guaranteed-to-be-unique identifier.
|
-- The main purpose is to avoid variable capture in macros.
|
--
|
-- If a string is passed as an argument, theis string will be part of the
|
-- id name (helpful for macro debugging)
|
--------------------------------------------------------------------------------
|
local gensymidx = 0
|
|
function M.gensym (arg)
|
gensymidx = gensymidx + 1
|
return { tag="Id", string.format(".%i.%s", gensymidx, arg or "")}
|
end
|
|
|
-------------------------------------------------------------------------------
|
-- parser metatable, which maps __call to method parse, and adds some
|
-- error tracing boilerplate.
|
-------------------------------------------------------------------------------
|
local parser_metatable = { }
|
|
function parser_metatable :__call (lx, ...)
|
return self :parse (lx, ...)
|
end
|
|
-------------------------------------------------------------------------------
|
-- Turn a table into a parser, mainly by setting the metatable.
|
-------------------------------------------------------------------------------
|
function M.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 M.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
|
local e=p[i]
|
if type(e) == "string" then
|
local kw = lx :next()
|
if not lx :is_keyword (kw, e) then
|
M.parse_error(
|
lx, "A keyword was expected, probably `%s'.", e)
|
end
|
elseif M.is_parser (e) then
|
table.insert (r, e(lx))
|
else -- Invalid parser definition, this is *not* a parsing error
|
error(string.format(
|
"Sequence `%s': element #%i is neither a string nor a parser: %s",
|
p.name, i, pp.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 = lexer.new_lineinfo(fli, lli)
|
end
|
end
|
return ast
|
end
|
|
-------------------------------------------------------------------------------
|
-- Generate a tracable parsing error (not implemented yet)
|
-------------------------------------------------------------------------------
|
function M.parse_error(lx, fmt, ...)
|
local li = lx:lineinfo_left()
|
local file, line, column, offset, positions
|
if li then
|
file, line, column, offset = li.source, li.line, li.column, li.offset
|
positions = { first = li, last = li }
|
else
|
line, column, offset = -1, -1, -1
|
end
|
|
local msg = string.format("line %i, char %i: "..fmt, line, column, ...)
|
if file and file~='?' then msg = "file "..file..", "..msg end
|
|
local src = lx.src
|
if offset>0 and src then
|
local i, j = offset, offset
|
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 (" ", column).."^"
|
msg = string.format("%s\n>>> %s\n>>> %s", msg, srcline, idx)
|
end
|
--lx :kill()
|
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 M.sequence (p)
|
M.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 = "unnamed_sequence"
|
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 M.multisequence (p)
|
M.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 M.is_parser(s) then M.sequence(s) end
|
if M.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
|
else
|
if self.sequences[keyword] then -- duplicate keyword
|
-- TODO: warn that initial keyword `keyword` is overloaded in multiseq
|
end
|
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
|
-- TODO: warn that we try to delete a non-existent entry
|
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 the result
|
-- 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 M.expr (p)
|
M.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
|
M.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 M.is_parser(p[t]) then M.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 M.list (p)
|
M.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
|
local is_empty_list = self.terminators and (peek_is_in (self.terminators) or lx:peek().tag=="Eof")
|
if not is_empty_list then
|
repeat
|
local item = self.primary(lx)
|
table.insert (x, item) -- read one element
|
until
|
-- There's a separator list specified, and next token isn't in it.
|
-- Otherwise, consume it with [lx:next()]
|
self.separators and not(peek_is_in (self.separators) and lx:next()) or
|
-- 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-conditioned 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 conditioning 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 M.onkeyword (p)
|
M.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 li = content.lineinfo or { }
|
fli, lli = li.first or fli, li.last or lli
|
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 M.is_parser (x)); p.primary = x end
|
end
|
assert (next (p.keywords), "Missing trigger keyword in gg.onkeyword")
|
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 M.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 M.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 M.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
|
|
--------------------------------------------------------------------------------
|
--
|
-- Make sure a parser is used and returns successfully.
|
--
|
--------------------------------------------------------------------------------
|
function M.nonempty(primary)
|
local p = M.make_parser('non-empty list', { primary = primary, name=primary.name })
|
function p :parse (lx)
|
local fli = lx:lineinfo_right()
|
local content = self.primary (lx)
|
local lli = lx:lineinfo_left()
|
local li = content.lineinfo or { }
|
fli, lli = li.first or fli, li.last or lli
|
if #content == 0 then
|
M.parse_error (lx, "`%s' must not be empty.", self.name or "list")
|
else
|
return transform (content, self, fli, lli)
|
end
|
end
|
return p
|
end
|
|
local FUTURE_MT = { }
|
function FUTURE_MT:__tostring() return "<Proxy parser module>" end
|
function FUTURE_MT:__newindex(key, value) error "don't write in futures" end
|
function FUTURE_MT :__index (parser_name)
|
return function(...)
|
local p, m = rawget(self, '__path'), self.__module
|
if p then for _, name in ipairs(p) do
|
m=rawget(m, name)
|
if not m then error ("Submodule '"..name.."' undefined") end
|
end end
|
local f = rawget(m, parser_name)
|
if not f then error ("Parser '"..parser_name.."' undefined") end
|
return f(...)
|
end
|
end
|
|
function M.future(module, ...)
|
checks('table')
|
local path = ... and {...}
|
if path then for _, x in ipairs(path) do
|
assert(type(x)=='string', "Bad future arg")
|
end end
|
local self = { __module = module,
|
__path = path }
|
return setmetatable(self, FUTURE_MT)
|
end
|
|
return M
|
