From 98e54ce388233170cd3a3feb2bcc4449670ccabc Mon Sep 17 00:00:00 2001 From: Sergio Queiroz Date: Wed, 14 Dec 2016 08:16:29 -0300 Subject: Removing files related to the previous version (with labeled ordered choice) --- examples/recoveryRe.lua | 141 ------------------------------------------------ 1 file changed, 141 deletions(-) delete mode 100644 examples/recoveryRe.lua (limited to 'examples') diff --git a/examples/recoveryRe.lua b/examples/recoveryRe.lua deleted file mode 100644 index 3b83d88..0000000 --- a/examples/recoveryRe.lua +++ /dev/null @@ -1,141 +0,0 @@ -local re = require"relabel" - --- The `errinfo` table contains the list of labels that we will be using --- as well as the corresponding error message for each label, which will --- be used in our error reporting later on. -local errinfo = { - {"NoExp", "no expression found"}, - {"Extra", "extra characters found after the expression"}, - {"ExpTerm", "expected a term after the operator"}, - {"ExpExp", "expected an expression after the parenthesis"}, - {"MisClose", "missing a closing ')' after the expression"}, -} - --- We split the errinfo table into two tables: `labels` which is a --- mapping from the label names to its integer representation, and --- `errmsgs` which is a mapping from the label names to its --- corresponding error message. -local labels = {} -local errmsgs = {} - -for i, err in ipairs(errinfo) do - labels[err[1]] = i - errmsgs[err[1]] = err[2] -end - --- The `labels` table is especially useful for making our re grammar more --- readable through the use of the `setlabels` function which allows us --- to use the label names directly in the re grammar instead of the integers. -re.setlabels(labels) - --- The `errors` table will hold the list of errors recorded during parsing -local errors = {} - --- The `recorderror` function simply records the label and position of --- the failure (index in input string) into the `errors` table. --- Note: The unused `input` parameter is necessary, as this will be called --- by LPeg's match-time capture. -local function recorderror(input, pos, label) - table.insert(errors, {label, pos}) - return true -end - --- The `compute` function takes an alternating list of numbers and --- operators and computes the result of applying the operations --- to the numbers in a left to right order (no operator precedence). -local function compute(tokens) - local result = tokens[1] - for i = 2, #tokens, 2 do - if tokens[i] == '+' then - result = result + tokens[i+1] - elseif tokens[i] == '-' then - result = result - tokens[i+1] - elseif tokens[i] == '*' then - result = result * tokens[i+1] - elseif tokens[i] == '/' then - result = result / tokens[i+1] - else - error('unknown operation: ' .. tokens[i]) - end - end - return result -end - --- Our grammar is a simple arithmetic expression of integers that --- does not take operator precedence into account but allows grouping --- via parenthesis. We have incorporated some error recovery startegies --- to our grammar so that it may resume parsing even after encountering --- an error, which allows us to report more errors. -local g = re.compile([[ - S <- (Exp / ErrNoExp) (!. / ErrExtra) - Exp <- {| Term (op Operand)* |} -> compute - -- If we encounter a missing term/operand, we return a dummy instead. - Operand <- Term / ErrExpTerm /{ExpTerm} dummy - Term <- num / Group - -- If we encounter a missing closing parenthesis, we ignore it. - Group <- "(" InnerExp (")" / ErrMisClose /{MisClose} "") - -- If we encounter a missing inner expression, we skip to the next - -- closing parenthesis, and return a dummy in its place. - InnerExp <- Exp / ErrExpExp /{ExpExp} [^)]* dummy - - op <- {[-+*/]} - num <- [0-9]+ -> tonumber - - -- Before throwing an error, we make sure to record it first. - ErrNoExp <- ("" -> "NoExp" => recorderror) %{NoExp} - ErrExtra <- ("" -> "Extra" => recorderror) %{Extra} - ErrExpTerm <- ("" -> "ExpTerm" => recorderror) %{ExpTerm} - ErrExpExp <- ("" -> "ExpExp" => recorderror) %{ExpExp} - ErrMisClose <- ("" -> "MisClose" => recorderror) %{MisClose} - - dummy <- "" -> "0" -> tonumber -]], { - compute = compute; - recorderror = recorderror; - tonumber = tonumber; -}) - --- The `eval` function takes an input string to match against the grammar --- we've just defined. If the input string matches, then the result of the --- computation is returned, otherwise we return the error messages and --- positions of all the failures encountered. -local function eval(input) - local result, label, suffix = g:match(input) - if #errors == 0 then - return result - else - local out = {} - for i, err in ipairs(errors) do - local pos = err[2] - local msg = errmsgs[err[1]] - local line, col = re.calcline(input, pos) - table.insert(out, "syntax error: " .. msg .. " (line " .. line .. ", col " .. col .. ")") - end - errors = {} - return nil, table.concat(out, "\n") - end -end - -print(eval "98-76*(54/32)") ---> 37.125 - -print(eval "(1+1-1*2/2") ---> syntax error: missing a closing ')' after the expression (line 1, col 10) - -print(eval "(1+)-1*(2/2)") ---> syntax error: expected a term after the operator (line 1, col 4) - -print(eval "(1+1)-1*(/2)") ---> syntax error: expected an expression after the parenthesis (line 1, col 10) - -print(eval "1+(1-(1*2))/2x") ---> syntax error: extra characters found after the expression (line 1, col 14) - -print(eval "-1+(1-(1*2))/2") ---> syntax error: no expression found (line 1, col 1) - -print(eval "(1+1-1*(2/2+)-():") ---> syntax error: expected a term after the operator (line 1, col 13) ---> syntax error: expected an expression after the parenthesis (line 1, col 16) ---> syntax error: missing a closing ')' after the expression (line 1, col 17) ---> syntax error: extra characters found after the expression (line 1, col 17) -- cgit v1.2.3-55-g6feb