+++ /dev/null
-----------------------------------------------------------------------
--- Metalua: $Id: mlp_misc.lua,v 1.6 2006/11/15 09:07:50 fab13n Exp $
---
--- Summary: metalua parser, miscellaneous utility functions.
---
-----------------------------------------------------------------------
---
--- Copyright (c) 2006, Fabien Fleutot <metalua@gmail.com>.
---
--- This software is released under the MIT Licence, see licence.txt
--- for details.
---
-----------------------------------------------------------------------
--- History:
--- $Log: mlp_misc.lua,v $
--- Revision 1.6 2006/11/15 09:07:50 fab13n
--- debugged meta operators.
--- Added command line options handling.
---
--- Revision 1.5 2006/11/10 02:11:17 fab13n
--- compiler faithfulness to 5.1 improved
--- gg.expr extended
--- mlp.expr refactored
---
--- Revision 1.4 2006/11/09 09:39:57 fab13n
--- some cleanup
---
--- Revision 1.3 2006/11/07 04:38:00 fab13n
--- first bootstrapping version.
---
--- Revision 1.2 2006/11/05 15:08:34 fab13n
--- updated code generation, to be compliant with 5.1
---
-----------------------------------------------------------------------
-
---------------------------------------------------------------------------------
---
--- Exported API:
--- * [mlp.fget()]
--- * [mlp.id()]
--- * [mlp.opt_id()]
--- * [mlp.id_list()]
--- * [mlp.gensym()]
--- * [mlp.string()]
--- * [mlp.opt_string()]
--- * [mlp.id2string()]
---
---------------------------------------------------------------------------------
-
---require "gg"
---require "mll"
-
-module ("mlp", package.seeall)
-
---------------------------------------------------------------------------------
--- returns a function that takes the [n]th element of a table.
--- if [tag] is provided, then this element is expected to be a
--- table, and this table receives a "tag" field whose value is
--- set to [tag].
---
--- The primary purpose of this is to generate builders for
--- grammar generators. It has little purpose in metalua, as lambda has
--- a lightweight syntax.
---------------------------------------------------------------------------------
-
-function fget (n, tag)
- assert (type (n) == "number")
- if tag then
- assert (type (tag) == "string")
- return function (x)
- assert (type (x[n]) == "table")
- return {tag=tag, unpack(x[n])} end
- else
- return function (x) return x[n] end
- end
-end
-
-
---------------------------------------------------------------------------------
--- Try to read an identifier (possibly as a splice), or return [false] if no
--- id is found.
---------------------------------------------------------------------------------
-function opt_id (lx)
- local a = lx:peek();
- if lx:is_keyword (a, "-{") then
- local v = gg.sequence{ "-{", splice_content, "}" } (lx) [1]
- if v.tag ~= "Id" and v.tag ~= "Splice" then
- gg.parse_error(lx,"Bad id splice")
- end
- return v
- elseif a.tag == "Id" then return lx:next()
- else return false end
-end
-
---------------------------------------------------------------------------------
--- Mandatory reading of an id: causes an error if it can't read one.
---------------------------------------------------------------------------------
-function id (lx)
- return opt_id (lx) or gg.parse_error(lx,"Identifier expected")
-end
-
---------------------------------------------------------------------------------
--- Common helper function
---------------------------------------------------------------------------------
-id_list = gg.list { primary = mlp.id, separators = "," }
-
---------------------------------------------------------------------------------
--- 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 gensym (arg)
- gensymidx = gensymidx + 1
- return { tag="Id", _G.string.format(".%i.%s", gensymidx, arg or "")}
-end
-
---------------------------------------------------------------------------------
--- Converts an identifier into a string. Hopefully one day it'll handle
--- splices gracefully, but that proves quite tricky.
---------------------------------------------------------------------------------
-function id2string (id)
- --print("id2string:", disp.ast(id))
- if id.tag == "Id" then id.tag = "String"; return id
- elseif id.tag == "Splice" then
- assert (in_a_quote, "can't do id2string on an outermost splice")
- error ("id2string on splice not implemented")
- -- Evaluating id[1] will produce `Id{ xxx },
- -- and we want it to produce `String{ xxx }
- -- Morally, this is what I want:
- -- return `String{ `Index{ `Splice{ id[1] }, `Number 1 } }
- -- That is, without sugar:
- return {tag="String", {tag="Index", {tag="Splice", id[1] },
- {tag="Number", 1 } } }
- else error ("Identifier expected: ".._G.table.tostring(id, 'nohash')) end
-end
-
---------------------------------------------------------------------------------
--- Read a string, possibly spliced, or return an error if it can't
---------------------------------------------------------------------------------
-function string (lx)
- local a = lx:peek()
- if lx:is_keyword (a, "-{") then
- local v = gg.sequence{ "-{", splice_content, "}" } (lx) [1]
- if v.tag ~= "" and v.tag ~= "Splice" then
- gg.parse_error(lx,"Bad string splice")
- end
- return v
- elseif a.tag == "String" then return lx:next()
- else error "String expected" end
-end
-
---------------------------------------------------------------------------------
--- Try to read a string, or return false if it can't. No splice allowed.
---------------------------------------------------------------------------------
-function opt_string (lx)
- return lx:peek().tag == "String" and lx:next()
-end
-
---------------------------------------------------------------------------------
--- Chunk reader: block + Eof
---------------------------------------------------------------------------------
-function skip_initial_sharp_comment (lx)
- -- Dirty hack: I'm happily fondling lexer's private parts
- -- FIXME: redundant with lexer:newstream()
- lx :sync()
- local i = lx.src:match ("^#.-\n()", lx.i)
- if i then lx.i, lx.column_offset, lx.line = i, i, lx.line+1 end
-end
-
-local function _chunk (lx)
- if lx:peek().tag == 'Eof' then return { } -- handle empty files
- else
- skip_initial_sharp_comment (lx)
- local chunk = block (lx)
- if lx:peek().tag ~= "Eof" then error "End-of-file expected" end
- return chunk
- end
-end
-
--- chunk is wrapped in a sequence so that it has a "transformer" field.
-chunk = gg.sequence { _chunk, builder = unpack }
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projects / metalua.git / blobdiff