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local re = require 'relabel'
local terror = {}
local function newError(l, msg)
table.insert(terror, { l = l, msg = msg} )
end
newError("errSemi", "Error: missing ';'")
newError("errExpIf", "Error: expected expression after 'if'")
newError("errThen", "Error: expected 'then' keyword")
newError("errCmdSeq1", "Error: expected at least a command after 'then'")
newError("errCmdSeq2", "Error: expected at least a command after 'else'")
newError("errEnd", "Error: expected 'end' keyword")
newError("errCmdSeqRep", "Error: expected at least a command after 'repeat'")
newError("errUntil", "Error: expected 'until' keyword")
newError("errExpRep", "Error: expected expression after 'until'")
newError("errAssignOp", "Error: expected ':=' in assigment")
newError("errExpAssign", "Error: expected expression after ':='")
newError("errReadName", "Error: expected an identifier after 'read'")
newError("errWriteExp", "Error: expected expression after 'write'")
newError("errSimpExp", "Error: expected '(', ID, or number after '<' or '='")
newError("errTerm", "Error: expected '(', ID, or number after '+' or '-'")
newError("errFactor", "Error: expected '(', ID, or number after '*' or '/'")
newError("errExpFac", "Error: expected expression after '('")
newError("errClosePar", "Error: expected ')' after expression")
local labelCode = {}
for k, v in ipairs(terror) do
labelCode[v.l] = k
end
re.setlabels(labelCode)
local g = re.compile[[
Tiny <- CmdSeq
CmdSeq <- (Cmd (SEMICOLON / ErrSemi)) (Cmd (SEMICOLON / ErrSemi))*
Cmd <- IfCmd / RepeatCmd / ReadCmd / WriteCmd / AssignCmd
IfCmd <- IF (Exp / ErrExpIf) (THEN / ErrThen) (CmdSeq / ErrCmdSeq1) (ELSE (CmdSeq / ErrCmdSeq2) / '') (END / ErrEnd)
RepeatCmd <- REPEAT (CmdSeq / ErrCmdSeqRep) (UNTIL / ErrUntil) (Exp / ErrExpRep)
AssignCmd <- NAME (ASSIGNMENT / ErrAssignOp) (Exp / ErrExpAssign)
ReadCmd <- READ (NAME / ErrReadName)
WriteCmd <- WRITE (Exp / ErrWriteExp)
Exp <- SimpleExp ((LESS / EQUAL) (SimpleExp / ErrSimpExp) / '')
SimpleExp <- Term ((ADD / SUB) (Term / ErrTerm))*
Term <- Factor ((MUL / DIV) (Factor / ErrFactor))*
Factor <- OPENPAR (Exp / ErrExpFac) (CLOSEPAR / ErrClosePar) / NUMBER / NAME
ErrSemi <- %{errSemi}
ErrExpIf <- %{errExpIf}
ErrThen <- %{errThen}
ErrCmdSeq1 <- %{errCmdSeq1}
ErrCmdSeq2 <- %{errCmdSeq2}
ErrEnd <- %{errEnd}
ErrCmdSeqRep <- %{errCmdSeqRep}
ErrUntil <- %{errUntil}
ErrExpRep <- %{errExpRep}
ErrAssignOp <- %{errAssignOp}
ErrExpAssign <- %{errExpAssign}
ErrReadName <- %{errReadName}
ErrWriteExp <- %{errWriteExp}
ErrSimpExp <- %{errSimpExp}
ErrTerm <- %{errTerm}
ErrFactor <- %{errFactor}
ErrExpFac <- %{errExpFac}
ErrClosePar <- %{errClosePar}
ADD <- Sp '+'
ASSIGNMENT <- Sp ':='
CLOSEPAR <- Sp ')'
DIV <- Sp '/'
IF <- Sp 'if'
ELSE <- Sp 'else'
END <- Sp 'end'
EQUAL <- Sp '='
LESS <- Sp '<'
MUL <- Sp '*'
NAME <- Sp !RESERVED [a-z]+
NUMBER <- Sp [0-9]+
OPENPAR <- Sp '('
READ <- Sp 'read'
REPEAT <- Sp 'repeat'
SEMICOLON <- Sp ';'
SUB <- Sp '-'
THEN <- Sp 'then'
UNTIL <- Sp 'until'
WRITE <- Sp 'write'
RESERVED <- (IF / ELSE / END / READ / REPEAT / THEN / UNTIL / WRITE) ![a-z]+
Sp <- %s*
]]
local function mymatch(g, s)
local r, e, sfail = g:match(s)
if not r then
local line, col = re.calcline(s, #s - #sfail)
local msg = "Error at line " .. line .. " (col " .. col .. "): "
return r, msg .. terror[e].msg
end
return r
end
local s = [[
n := 5;
f := 1;
repeat
f := f + n;
n := n - 1
until (n < 1);
write f;]]
print(mymatch(g, s))
s = [[
n := 5;
f := 1;
repeat
f := f + n;
n := n - 1;
until (n < 1);
read ;]]
print(mymatch(g, s))
s = [[
if a < 1 then
b := 2;
else
b := 3;]]
print(mymatch(g, s))
s = [[
n := 5;
f := 1;
repeat
f := f + n;
n := n - 1;
untill (n < 1);
]]
print(mymatch(g, s))
s = [[
n := 5;
f := 1;
repeat
f := f + n;
n := n - 1;
3 (n < 1);
]]
print(mymatch(g, s))
print(mymatch(g, "a : 2"))
print(mymatch(g, "a := (2"))
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