-- parse.lua: functions to parse words keeping track of the column.
-- These functions are used to parse tree segments (in "%:" lines)
--   and 2D grids (in both "%D 2Dx" and "%D 2D" lines).
-- This file:
--   http://angg.twu.net/dednat6/dednat6/parse.lua.html
--   http://angg.twu.net/dednat6/dednat6/parse.lua
--           (find-angg "dednat6/dednat6/parse.lua")
-- Author: Eduardo Ochs <eduardoochs@gmail.com>
-- Version: 2021jan24
-- License: GPL3
--
-- Based on:
-- http://angg.twu.net/miniforth-article.html
-- http://angg.twu.net/miniforth/miniforth-article.pdf

-- «.getword»			(to "getword")
-- «.getword-with-errmsgs»	(to "getword-with-errmsgs")



setsubj = function (subj_, pos_)
    subj = subj_
    pos  = pos_ or 3
    startcol, endcol = 1, pos
  end

-- «getword» (to ".getword")
-- (find-dn5file "parse.lua" "getword =")
-- (find-dn5 "dednat6.lua" "utf8")
getword = function ()
    local spaces, word_, newpos = subj:match("( *)([^ ]+)()", pos)
    if spaces then
      startcol = endcol + #spaces
      endcol   = endcol + #spaces + word_:len8()   -- UTF-8
      word     = word_
      pos      = newpos
      return word
    end
  end

getwordasluaexpr = function ()
    local expr = getword()
    local code = "return "..expr
    return assert(loadstring(code))()
  end

getrestofline = function ()
    local spaces, word_, newpos = subj:match("( *)(.*)()", pos)
    if spaces then
      startcol = endcol + #spaces
      endcol   = endcol + #spaces + #word_   -- change for UTF-8
      word     = word_
      pos      = newpos
      return word
    end
  end

--[[
• (eepitch-lua51)
• (eepitch-kill)
• (eepitch-lua51)
dofile "parse.lua"
run = function (str)
    setsubj(str)
    while getword() do PP(startcol, endcol, pos, word) end
  end
run "%Dfoo bar  plic"

--]]



-- «getword-with-errmsgs»  (to ".getword-with-errmsgs")
-- These are higher-level variants of getword() and getwordasluaexpr()
-- that accept error messages. Mnemonic: they have "_"s in their
-- names, and "getword_lua" is more readable than "getwordlua".

getword_1 = function (funname, errmsg)
    errmsg = errmsg or "argument"
    return getword() or error(format("In '%s': missing %s", funname, errmsg))
  end
getword_2 = function (funname, errmsg1, errmsg2)
    local a = getword_1(funname, errmsg1 or "first argument")
    local b = getword_1(funname, errmsg2 or "second argument")
    return a,b
  end

getword_lua = function (funname, errmsg)
    return expr(getword_1(funname, errmsg))
  end
getword_lualua = function (funname, errmsg1, errmsg2)
    local a, b = getword_2(funname, errmsg1, errmsg2)
    return expr(a), expr(b)
  end




-- Local Variables:
-- coding:             utf-8-unix
-- End: