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461 lines (425 loc) · 13 KB
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--- Lexical scanner for creating a sequence of tokens from text. <br>
-- <p><code>lexer.scan(s)</code> returns an iterator over all tokens found in the
-- string <code>s</code>. This iterator returns two values, a token type string
-- (such as 'string' for quoted string, 'iden' for identifier) and the value of the
-- token.
-- <p>
-- Versions specialized for Lua and C are available; these also handle block comments
-- and classify keywords as 'keyword' tokens. For example:
-- <pre class=example>
-- > s = 'for i=1,n do'
-- > for t,v in lexer.lua(s) do print(t,v) end
-- keyword for
-- iden i
-- = =
-- number 1
-- , ,
-- iden n
-- keyword do
-- </pre>
-- See the Guide for further <a href="../../index.html#lexer">discussion</a> <br>
-- @class module
-- @name pl.lexer
local strfind = string.find
local strsub = string.sub
local append = table.insert
--[[
module ('pl.lexer',utils._module)
]]
local function assert_arg(idx,val,tp)
if type(val) ~= tp then
error("argument "..idx.." must be "..tp, 2)
end
end
local lexer = {}
local NUMBER1 = '^[%+%-]?%d+%.?%d*[eE][%+%-]?%d+'
local NUMBER2 = '^[%+%-]?%d+%.?%d*'
local NUMBER3 = '^0x[%da-fA-F]+'
local NUMBER4 = '^%d+%.?%d*[eE][%+%-]?%d+'
local NUMBER5 = '^%d+%.?%d*'
local IDEN = '^[%a_][%w_]*'
local WSPACE = '^%s+'
local STRING1 = [[^'.-[^\\]']]
local STRING2 = [[^".-[^\\]"]]
local STRING3 = "^((['\"])%2)" -- empty string
local PREPRO = '^#.-[^\\]\n'
local plain_matches,lua_matches,cpp_matches,lua_keyword,cpp_keyword
local function tdump(tok)
return tok,tok
end
local function ndump(tok,options)
if options and options.number then
tok = tonumber(tok)
end
return "number",tok
end
-- regular strings, single or double quotes; usually we want them
-- without the quotes
local function sdump(tok,options)
if options and options.string then
tok = tok:sub(2,-2)
end
return "string",tok
end
-- long Lua strings need extra work to get rid of the quotes
local function sdump_l(tok,options)
if options and options.string then
tok = tok:sub(3,-3)
end
return "string",tok
end
local function chdump(tok,options)
if options and options.string then
tok = tok:sub(2,-2)
end
return "char",tok
end
local function cdump(tok)
return 'comment',tok
end
local function wsdump (tok)
return "space",tok
end
local function pdump (tok)
return 'prepro',tok
end
local function plain_vdump(tok)
return "iden",tok
end
local function lua_vdump(tok)
if lua_keyword[tok] then
return "keyword",tok
else
return "iden",tok
end
end
local function cpp_vdump(tok)
if cpp_keyword[tok] then
return "keyword",tok
else
return "iden",tok
end
end
local function count_lines(line, text)
local index, limit = 1, #text
while index <= limit do
local start, stop = text:find('\r\n', index, true)
if not start then
start, stop = text:find('[\r\n\f]', index)
if not start then break end
end
index = stop + 1
line = line + 1
end
return line
end
local multiline = { comment = true, space = true }
--- create a plain token iterator from a string or file-like object.
-- @param s the string
-- @param matches an optional match table (set of pattern-action pairs)
-- @param filter a table of token types to exclude, by default {space=true}
-- @param options a table of options; by default, {number=true,string=true},
-- which means convert numbers and strip string quotes.
function lexer.scan (s,matches,filter,options)
--assert_arg(1,s,'string')
local file = type(s) ~= 'string' and s
filter = filter or {space=true}
options = options or {number=true,string=true}
if filter then
if filter.space then filter[wsdump] = true end
if filter.comments then
filter[cdump] = true
end
end
if not matches then
if not plain_matches then
plain_matches = {
{WSPACE,wsdump},
{NUMBER3,ndump},
{IDEN,plain_vdump},
{NUMBER1,ndump},
{NUMBER2,ndump},
{STRING3,sdump},
{STRING1,sdump},
{STRING2,sdump},
{'^.',tdump}
}
end
matches = plain_matches
end
local i1,i2,idx,res1,res2,tok,pat,fun,capt
local line = 1
if file then
s = file:read()
if not s then return nil end -- empty file
s = s ..'\n'
end
local sz = #s
local idx = 1
if sz == 0 then return nil end -- empty file
local res = {}
local mt = {}
mt.__index = mt
setmetatable(res,mt)
function mt.lineno() return line end
function mt.getline()
if idx < sz then
tok = strsub(s,idx,-2)
idx = sz + 1
line = line + 1
return tok
else
idx = sz + 1
line = line + 1
return file:read()
end
end
function mt.next (tok)
local t,v = tok()
while t == 'space' do
t,v = tok()
end
return t,v
end
function mt.__call ()
if not s then return end
while true do
for _,m in ipairs(matches) do
pat,fun = m[1],m[2]
if fun == nil then error("no match for "..pat) end
i1,i2 = strfind(s,pat,idx)
if i1 then
tok = strsub(s,i1,i2)
idx = i2 + 1
if not (filter and filter[fun]) then
lexer.finished = idx > sz
local t,v = fun(tok,options)
if not file and multiline[t] then
line = count_lines(line,v)
end
return t,v
end
end
end
if idx > sz then
if file then
line = line + 1
s = file:read()
if not s then return end
s = s .. '\n'
idx ,sz = 1,#s
else
return
end
end
end
end
return res
end
--- get everything in a stream upto a newline.
-- @param tok a token stream
-- @return a string
function lexer.getline (tok)
return tok:getline()
end
--- get current line number. <br>
-- Only available if the input source is a file-like object.
-- @param tok a token stream
-- @return the line number and current column
function lexer.lineno (tok)
return tok:lineno()
end
--- get the Lua keywords as a set-like table.
-- So <code>res["and"]</code> etc would be <code>true</code>.
-- @return a table
function lexer.get_keywords ()
if not lua_keyword then
lua_keyword = {
["and"] = true, ["break"] = true, ["do"] = true,
["else"] = true, ["elseif"] = true, ["end"] = true,
["false"] = true, ["for"] = true, ["function"] = true,
["if"] = true, ["in"] = true, ["local"] = true, ["nil"] = true,
["not"] = true, ["or"] = true, ["repeat"] = true,
["return"] = true, ["then"] = true, ["true"] = true,
["until"] = true, ["while"] = true
}
end
return lua_keyword
end
--- create a Lua token iterator from a string or file-like object.
-- Will return the token type and value.
-- @param s the string
-- @param filter a table of token types to exclude, by default {space=true,comments=true}
-- @param options a table of options; by default, {number=true,string=true},
-- which means convert numbers and strip string quotes.
function lexer.lua(s,filter,options)
filter = filter or {space=true,comments=true}
lexer.get_keywords()
if not lua_matches then
lua_matches = {
{WSPACE,wsdump},
{NUMBER3,ndump},
{IDEN,lua_vdump},
{NUMBER4,ndump},
{NUMBER5,ndump},
{STRING3,sdump},
{STRING1,sdump},
{STRING2,sdump},
{'^%-%-%[(=*)%[.-%]%1%]',cdump},
{'^%-%-.-\n',cdump},
{'^%[(=*)%[.-%]%1%]',sdump_l},
{'^==',tdump},
{'^~=',tdump},
{'^<=',tdump},
{'^>=',tdump},
{'^%.%.%.',tdump},
{'^%.%.',tdump},
{'^.',tdump}
}
end
return lexer.scan(s,lua_matches,filter,options)
end
--- create a C/C++ token iterator from a string or file-like object.
-- Will return the token type type and value.
-- @param s the string
-- @param filter a table of token types to exclude, by default {space=true,comments=true}
-- @param options a table of options; by default, {number=true,string=true},
-- which means convert numbers and strip string quotes.
function lexer.cpp(s,filter,options)
filter = filter or {comments=true}
if not cpp_keyword then
cpp_keyword = {
["class"] = true, ["break"] = true, ["do"] = true, ["sizeof"] = true,
["else"] = true, ["continue"] = true, ["struct"] = true,
["false"] = true, ["for"] = true, ["public"] = true, ["void"] = true,
["private"] = true, ["protected"] = true, ["goto"] = true,
["if"] = true, ["static"] = true, ["const"] = true, ["typedef"] = true,
["enum"] = true, ["char"] = true, ["int"] = true, ["bool"] = true,
["long"] = true, ["float"] = true, ["true"] = true, ["delete"] = true,
["double"] = true, ["while"] = true, ["new"] = true,
["namespace"] = true, ["try"] = true, ["catch"] = true,
["switch"] = true, ["case"] = true, ["extern"] = true,
["return"] = true,["default"] = true,['unsigned'] = true,['signed'] = true,
["union"] = true, ["volatile"] = true, ["register"] = true,["short"] = true,
}
end
if not cpp_matches then
cpp_matches = {
{WSPACE,wsdump},
{PREPRO,pdump},
{NUMBER3,ndump},
{IDEN,cpp_vdump},
{NUMBER4,ndump},
{NUMBER5,ndump},
{STRING3,sdump},
{STRING1,chdump},
{STRING2,sdump},
{'^//.-\n',cdump},
{'^/%*.-%*/',cdump},
{'^==',tdump},
{'^!=',tdump},
{'^<=',tdump},
{'^>=',tdump},
{'^->',tdump},
{'^&&',tdump},
{'^||',tdump},
{'^%+%+',tdump},
{'^%-%-',tdump},
{'^%+=',tdump},
{'^%-=',tdump},
{'^%*=',tdump},
{'^/=',tdump},
{'^|=',tdump},
{'^%^=',tdump},
{'^::',tdump},
{'^.',tdump}
}
end
return lexer.scan(s,cpp_matches,filter,options)
end
--- get a list of parameters separated by a delimiter from a stream.
-- @param tok the token stream
-- @param endtoken end of list (default ')'). Can be '\n'
-- @param delim separator (default ',')
-- @return a list of token lists.
function lexer.get_separated_list(tok,endtoken,delim)
endtoken = endtoken or ')'
delim = delim or ','
local function tappend (tl,t,val)
val = val or t
append(tl,{t,val})
end
local is_end
if endtoken == '\n' then
is_end = function(t,val)
return t == 'space' and val:find '\n'
end
else
is_end = function (t)
return t == endtoken
end
end
local is_delim
if type(delim) == 'function' then
is_delim = delim
else
is_delim = function(t)
return t == delim
end
end
local parm_values = {}
local level = 1 -- used to count ( and )
local tl = {}
local token,value
while true do
token,value=tok()
if not token then return nil,'EOS' end -- end of stream is an error!
if is_end(token,value) and level == 1 then
if next(tl) then
append(parm_values,tl)
end
break
elseif token == '(' then
level = level + 1
tappend(tl,'(')
elseif token == ')' then
level = level - 1
if level == 0 then -- finished with parm list
append(parm_values,tl)
break
else
tappend(tl,')')
end
elseif level == 1 and is_delim(token) then
append(parm_values,tl) -- a new parm
tl = {}
else
tappend(tl,token,value)
end
end
return parm_values,{token,value}
end
--- get the next non-space token from the stream.
-- @param tok the token stream.
function lexer.skipws (tok)
return tok:next()
end
local skipws = lexer.skipws
--- get the next token, which must be of the expected type.
-- Throws an error if this type does not match!
-- @param tok the token stream
-- @param expected_type the token type
-- @param no_skip_ws whether we should skip whitespace
function lexer.expecting (tok,expected_type,no_skip_ws)
assert_arg(1,tok,'function')
assert_arg(2,expected_type,'string')
local t,v
if no_skip_ws then
t,v = tok()
else
t,v = skipws(tok)
end
if t ~= expected_type then error ("expecting "..expected_type,2) end
return v
end
return lexer