334 lines
9.7 KiB
Lua
334 lines
9.7 KiB
Lua
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local re = require "lpeglabel.relabel"
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local peg = {}
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-- from relabel.lua
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local errinfo = {
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{"NoPatt", "no pattern found"},
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{"ExtraChars", "unexpected characters after the pattern"},
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{"ExpPatt1", "expected a pattern after '/' or '//{...}'"},
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{"ExpPatt2", "expected a pattern after '&'"},
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{"ExpPatt3", "expected a pattern after '!'"},
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{"ExpPatt4", "expected a pattern after '('"},
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{"ExpPatt5", "expected a pattern after ':'"},
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{"ExpPatt6", "expected a pattern after '{~'"},
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{"ExpPatt7", "expected a pattern after '{|'"},
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{"ExpPatt8", "expected a pattern after '<-'"},
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{"ExpPattOrClose", "expected a pattern or closing '}' after '{'"},
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{"ExpNum", "expected a number after '^', '+' or '-' (no space)"},
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{"ExpNumOrLab", "expected a number or a label after ^"},
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{"ExpCap", "expected a string, number, '{}' or name after '->'"},
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{"ExpName1", "expected the name of a rule after '=>'"},
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{"ExpName2", "expected the name of a rule after '=' (no space)"},
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{"ExpName3", "expected the name of a rule after '<' (no space)"},
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{"ExpLab1", "expected at least one label after '{'"},
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{"ExpLab2", "expected a label after the comma"},
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{"ExpNameOrLab", "expected a name or label after '%' (no space)"},
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{"ExpItem", "expected at least one item after '[' or '^'"},
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{"MisClose1", "missing closing ')'"},
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{"MisClose2", "missing closing ':}'"},
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{"MisClose3", "missing closing '~}'"},
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{"MisClose4", "missing closing '|}'"},
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{"MisClose5", "missing closing '}'"}, -- for the captures
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{"MisClose6", "missing closing '>'"},
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{"MisClose7", "missing closing '}'"}, -- for the labels
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{"MisClose8", "missing closing ']'"},
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{"MisTerm1", "missing terminating single quote"},
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{"MisTerm2", "missing terminating double quote"},
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}
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local errmsgs = {}
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local labels = {}
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for i, err in ipairs(errinfo) do
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errmsgs[i] = err[2]
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labels[err[1]] = i
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end
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re.setlabels(labels)
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local function concat(a,b)
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return a..b
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end
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local function foldtable(action,t)
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local re
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local first = true
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for key,value in pairs(t) do
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if first then
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re = value
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first = false
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else
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local temp = re
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if action == "suf" then -- suffix actions
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local act = value[1]
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if act == "*" or act == "?" or act == "+" then
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re = {action=act, op1=temp}
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else
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re = {action=act, op1=temp, op2=value[2]}
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end
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elseif action == "or" and #value == 2 then -- recovery expression
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local labels = value[1]
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local op2 = value[2]
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re = {action=action, op1=temp, op2=op2, condition=labels}
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else
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re = {action=action, op1=temp, op2=value}
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end
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end
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end
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return re
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end
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local gram = [=[
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pattern <- (exp / %{NoPatt}) (!. / %{ExtraChars})
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exp <- S (grammar / alternative)
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labels <- {| '{' {: (label / %{ExpLab1}) :} (',' {: (label / %{ExpLab2}) :})* ('}' / %{MisClose7}) |}
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alternative <- ( {:''->'or':} {| {: seq :} ('/' (('/' {| {: labels :} S {: (seq / %{ExpPatt1}) :} |}) / (S {: (seq / %{ExpPatt1}) :} ) ) )* |} ) -> foldtable
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seq <- ( {:''->'and':} {| {: prefix :}+ |} ) -> foldtable
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prefix <- {| {:action: '&' :} S {:op1: (prefix / %{ExpPatt2}) :} |}
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/ {| {:action: '!' :} S {:op1: (prefix / %{ExpPatt3}) :} |}
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/ suffix
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suffix <- ( {:''->'suf':} {| primary S {| suffixaction S |}* |} ) -> foldtable
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suffixaction <- {[+*?]}
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/ {'^'} {| {:num: [+-]? NUM:} |}
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/ '^'->'^LABEL' (label / %{ExpNumOrLab})
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/ {'->'} S ((string / {| {:action:'{}'->'poscap':} |} / funcname / {|{:num: NUM :} |}) / %{ExpCap})
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/ {'=>'} S (funcname / %{ExpName1})
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primary <- '(' (exp / %{ExpPatt4}) (')' / %{MisClose1})
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/ term
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/ class
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/ defined
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/ {| {:action: '%'->'label':} ('{' / %{ExpNameOrLab}) S ({:op1: label:} / %{ExpLab1}) S ('}' / %{MisClose7}) |}
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/ {| {:action: '{:'->'gcap':} {:op2: defname:} ':' !'}' ({:op1:exp:} / %{ExpPatt5}) (':}' / %{MisClose2}) |}
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/ {| {:action: '{:'->'gcap':} ({:op1:exp:} / %{ExpPatt5}) (':}' / %{MisClose2}) |}
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/ {| {:action: '='->'bref':} ({:op1: defname:} / %{ExpName2}) |}
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/ {| {:action: '{}'->'poscap':} |}
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/ {| {:action: '{~'->'subcap':} ({:op1: exp:} / %{ExpPatt6}) ('~}' / %{MisClose3}) |}
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/ {| {:action: '{|'->'tcap':} ({:op1: exp:} / %{ExpPatt7}) ('|}' / %{MisClose4}) |}
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/ {| {:action: '{'->'scap':} ({:op1: exp:} / %{ExpPattOrClose}) ('}' / %{MisClose5}) |}
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/ {| {:action: '.'->'anychar':} |}
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/ !frag !nodee name S !ARROW
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/ '<' (name / %{ExpName3}) ('>' / %{MisClose6}) -- old-style non terminals
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grammar <- {| definition+ |}
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definition <- {| (frag / nodee)? (token / nontoken) S ARROW ({:rule: exp :} / %{ExpPatt8}) |}
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label <- {| {:s: ERRORNAME :} |}
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frag <- {:fragment: 'fragment'->'1' :} ![0-9_a-z] S !ARROW
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nodee <- {:node: 'node'->'1' :} ![0-9_a-z] S !ARROW
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token <- {:rulename: TOKENNAME :} {:token:''->'1':}
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nontoken <- {:rulename: NAMESTRING :}
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class <- '[' ( ('^' {| {:action:''->'invert':} {:op1: classset :} |} ) / classset ) (']' / %{MisClose8})
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classset <- ( {:''->'or':} {| {: (item / %{ExpItem}) :} (!']' {: (item / %{ExpItem}) :})* |} ) -> foldtable
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item <- defined / range / {| {:t: . :} |}
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range <- {| {:action:''->'range':} {:op1: {| {:s: ({: . :} ('-') {: [^]] :} ) -> concat :} |} :} |}
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S <- (%s / '--' [^%nl]*)* -- spaces and comments
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name <- {| {:nt: TOKENNAME :} {:token:''->'1':} / {:nt: NAMESTRING :} |}
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funcname <- {| {:func: NAMESTRING :} |}
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ERRORNAME <- NAMESTRING
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NAMESTRING <- [A-Za-z][A-Za-z0-9_]*
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TOKENNAME <- [A-Z_]+ ![0-9a-z]
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defname <- {| {:s: NAMESTRING :} |}
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ARROW <- '<-'
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NUM <- [0-9]+
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term <- {| '"' {:t: [^"]* :} ('"' / %{MisTerm2}) / "'" {:t: [^']* :} ("'" / %{MisTerm1}) |}
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string <- {| '"' {:s: [^"]* :} ('"' / %{MisTerm2}) / "'" {:s: [^']* :} ("'" / %{MisTerm1}) |}
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defined <- {| {:action: '%':} {:op1: defname :} |}
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]=]
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local defs = {foldtable=foldtable, concat=concat}
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peg.gram = gram
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peg.defs = defs
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peg.labels = labels
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local p = re.compile ( gram, defs)
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--[[
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Function: pegToAST(input)
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Input: a grammar in PEG format, described in https://github.com/vsbenas/parser-gen
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Output: if parsing successful - a table of grammar rules, else - runtime error
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Example input: "
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Program <- stmt* / SPACE
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stmt <- ('a' / 'b')+
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SPACE <- ''
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"
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Example output: {
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{rulename = "Program", rule = {action = "or", op1 = {action = "*", op1 = {nt = "stmt"}}, op2 = {nt = "SPACE", token="1"}}},
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{rulename = "stmt", rule = {action = "+", op1 = {action="or", op1 = {t = "a"}, op2 = {t = "b"}}}},
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{rulename = "SPACE", rule = {t=""}, token=1},
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}
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The rules are further processed and turned into lpeg compatible format in parser-gen.lua
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Action names:
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or (has parameter condition for recovery expresions)
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and
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&
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!
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+
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*
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?
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^num (num is a number with an optional plus or minus sign)
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^label (label is an error label set with setlabels)
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->
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=>
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tcap
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gcap (op2= name, anonymous otherwise)
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bref
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poscap
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subcap
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scap
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anychar
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label
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%
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range
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Final token actions:
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t - terminal
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nt - non terminal
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func - function definition
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s - literal string
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num - literal number
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]]--
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local function splitlines(str)
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local t = {}
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local function helper(line) table.insert(t, line) return "" end
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helper((str:gsub("(.-)\r?\n", helper)))
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return t
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end
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function peg.pegToAST(input, defs)
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local r, e, sfail = p:match(input, defs)
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if not r then
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local lab
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if e == 0 then
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lab = "Syntax error"
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else
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lab = errmsgs[e]
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end
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local lines = splitlines(input)
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local line, col = re.calcline(input, #input - #sfail + 1)
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local err = {}
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table.insert(err, "L" .. line .. ":C" .. col .. ": " .. lab)
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table.insert(err, lines[line])
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table.insert(err, string.rep(" ", col-1) .. "^")
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error("syntax error(s) in pattern\n" .. table.concat(err, "\n"), 3)
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end
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return r
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end
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function peg.print_r ( t ) -- for debugging
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local print_r_cache={}
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local function sub_print_r(t,indent)
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if (print_r_cache[tostring(t)]) then
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print(indent.."*"..tostring(t))
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else
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print_r_cache[tostring(t)]=true
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if (type(t)=="table") then
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for pos,val in pairs(t) do
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if (type(val)=="table") then
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print(indent.."["..pos.."] => {")
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sub_print_r(val,indent..string.rep(" ",string.len(pos)+8))
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print(indent..string.rep(" ",string.len(pos)+6).."}")
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else
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print(indent.."["..pos.."] => '"..tostring(val).."'")
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end
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end
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else
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print(indent..tostring(t))
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end
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end
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end
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sub_print_r(t,"")
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end
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function peg.print_t ( t ) -- for debugging
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local print_r_cache={}
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local function sub_print_r (t,indent)
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if (print_r_cache[tostring(t)]) then
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print(indent.."*"..tostring(t))
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else
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print_r_cache[tostring(t)]=true
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if (type(t)=="table") then
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local function subprint (pos,val,indent)
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if (type(val)=="table") then
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print(indent.."{")
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sub_print_r(val,indent..string.rep(" ",string.len(pos)+8))
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print(indent..string.rep(" ",string.len(pos)-1).."},")
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else
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if type(val) ~= "number" then
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val = "'"..tostring(val).."'"
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end
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if tonumber(pos) then
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print(indent..val..",")
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else
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print(indent..pos.."="..val..",")
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end
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end
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end
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if t["rule"] then
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subprint("rule",t["rule"],indent)
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end
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if t["pos"] then
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subprint("pos",t["pos"],indent)
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end
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for pos,val in pairs(t) do
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if pos ~= "rule" and pos ~= "pos" then
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subprint(pos,val,indent)
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end
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end
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else
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print(indent..tostring(t))
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end
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end
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end
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sub_print_r(t,"")
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end
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function peg.calcline(subject, pos)
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return re.calcline(subject,pos)
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end
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return peg
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