1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
|
local m = require'lpeglabel'
local re = require'relabel'
local id = m.R'az'^1
local g = m.P{
"S",
S = m.V"Id" * m.V"List",
List = -m.P(1) + m.V"Comma" * m.V"Id" * m.V"List",
Id = m.V"Sp" * id + m.T'ErrId',
Comma = m.V"Sp" * "," + m.T'ErrComma',
Sp = m.S" \n\t"^0,
}
function mymatch (g, s)
local r, e, pos = g:match(s)
if not r then
local line, col = re.calcline(s, pos)
local msg = "Error at line " .. line .. " (col " .. col .. ")"
if e == 'ErrId' then
return r, msg .. ": expecting an identifier before '" .. s:sub(pos) .. "'"
elseif e == 'ErrComma' then
return r, msg .. ": expecting ',' before '" .. s:sub(pos) .. "'"
else
return r, msg
end
end
return r
end
print(mymatch(g, "one,two"))
print(mymatch(g, "one two"))
print(mymatch(g, "one,\n two,\nthree,"))
|
