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lexer.grace
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lexer.grace
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#pragma DefaultVisibility=public
def io = platform.io
def sys = platform.sys
def util = platform.util
def unicode = platform.unicode
def mgcollections = platform.mgcollections
def collections = mgcollections
// Return the numeric value of the single hexadecimal character c.
method hexdecchar(c) {
var chars := ["0", "1", "2", "3", "4", "5", "6", "7", "8",
"9", "a", "b", "c", "d", "e", "f"]
var ret := 0
var i := 0
for (chars) do {cr->
if (cr == c) then {
ret := i
}
i := i + 1
}
ret
}
def LexerClass = object {
method new {
var lineNumber := 1
var linePosition := 0
var startPosition := 1
var indentLevel := 0
class IdentifierToken.new(s) {
def kind = "identifier"
def value = s
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class StringToken.new(s) {
def kind = "string"
def value = s
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class OctetsToken.new(s) {
def kind = "octets"
def value = s
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class LBraceToken.new {
def kind = "lbrace"
def value = "\{"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class RBraceToken.new {
def kind = "rbrace"
def value = "}"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class LParenToken.new {
def kind = "lparen"
def value = "("
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class RParenToken.new {
def kind = "rparen"
def value = ")"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class LSquareToken.new {
def kind = "lsquare"
def value = "["
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class RSquareToken.new {
def kind = "rsquare"
def value = "]"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class CommaToken.new {
def kind = "comma"
def value = ","
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class ColonToken.new {
def kind = "colon"
def value = ":"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class DotToken.new {
def kind = "dot"
def value = "."
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class NumToken.new(v) {
def kind = "num"
def value = v
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class KeywordToken.new(v) {
def kind = "keyword"
def value = v
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class OpToken.new(v) {
def kind = "op"
def value = v
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class ArrowToken.new {
def kind = "arrow"
def value = "->"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class BindToken.new {
def kind = "bind"
def value = ":="
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class SemicolonToken.new {
def kind = "semicolon"
def value = ";"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class LGenericToken.new {
def kind = "lgeneric"
def value = "<"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
class RGenericToken.new {
def kind = "rgeneric"
def value = ">"
def line = lineNumber
def indent = indentLevel
def linePos = startPosition
}
object {
// When a new lexical class has begun, add to the tokens list
// the token corresponding to the previous accumulated data.
// mode is the previous lexical mode (a string), and accum the
// accumulated characters since that mode began. Modes are:
// n Whitespace i Identifier
// " Quoted string x Octets literal
// m Number o Any operator
// c Comment
// ,.{}[] The corresponding literal character
//
// There are three special cases for mode o. If accum is "->",
// ":=", or "=", the corresponding special token is created.
// For mode i, a keyword token is created for an identifier
// whose name is a reserved keyword.
method modechange(tokens, mode, accum) {
var done := false
var tok := 0
if ((mode != "n") || (accum.size > 0)) then {
if (mode == "i") then {
tok := IdentifierToken.new(accum)
if ((accum == "object") || (accum == "method")
|| (accum == "var") || (accum == "type")
|| (accum == "import") || (accum == "class")
|| (accum == "return") || (accum == "def")
|| (accum == "inherits") || (accum == "is")) then {
tok := KeywordToken.new(accum)
}
tokens.push(tok)
done := true
}
if (mode == "I") then {
tok := IdentifierToken.new(accum)
tokens.push(tok)
done := true
} elseif (mode == "\"") then {
tok := StringToken.new(accum)
tokens.push(tok)
done := true
} elseif (mode == "x") then {
tok := OctetsToken.new(accum)
tokens.push(tok)
done := true
} elseif (mode == ",") then {
tok := CommaToken.new
tokens.push(tok)
done := true
} elseif (mode == ".") then {
tok := DotToken.new
tokens.push(tok)
done := true
} elseif (mode == "\{") then {
tok := LBraceToken.new
tokens.push(tok)
done := true
} elseif (mode == "}") then {
tok := RBraceToken.new
tokens.push(tok)
done := true
} elseif (mode == "(") then {
tok := LParenToken.new
tokens.push(tok)
done := true
} elseif (mode == ")") then {
tok := RParenToken.new
tokens.push(tok)
done := true
} elseif (mode == "[") then {
tok := LSquareToken.new
tokens.push(tok)
done := true
}
if (mode == "]") then {
tok := RSquareToken.new
tokens.push(tok)
done := true
} elseif (mode == "<") then {
tok := LGenericToken.new
tokens.push(tok)
done := true
} elseif (mode == ">") then {
tok := RGenericToken.new
tokens.push(tok)
done := true
} elseif (mode == ";") then {
tok := SemicolonToken.new
tokens.push(tok)
done := true
} elseif (mode == "m") then {
tok := NumToken.new(accum)
tok := makeNumToken(accum)
if (tokens.size > 1) then {
if (tokens.last.kind == "dot") then {
tokens.pop
if (tokens.last.kind == "num") then {
tok := tokens.pop
tok := NumToken.new(tok.value ++ "." ++ accum)
} else {
util.syntax_error("found ." ++ accum
++ ", expected term")
}
}
}
tokens.push(tok)
done := true
} elseif (mode == "o") then {
tok := OpToken.new(accum)
if (accum == "->") then {
tok := ArrowToken.new
} elseif (accum == ":=") then {
tok := BindToken.new
} elseif (accum == ":") then {
tok := ColonToken.new
}
tokens.push(tok)
done := true
} elseif (mode == "d") then {
indentLevel := accum.size
done := true
} elseif (mode == "n") then {
done := true
} elseif (mode == "c") then {
done := true
} elseif (mode == "p") then {
if (accum.substringFrom(1)to(8) == "#pragma ") then {
util.processExtension(
accum.substringFrom(9)to(accum.size))
}
} elseif (done) then {
//print(mode, accum, tokens)
} else {
util.syntax_error("Lexing error: no handler for mode " ++ mode ++
" with accum " ++ accum)
}
}
startPosition := linePosition
}
def cLines = collections.list.new
def lines = collections.list.new
method fromBase(str, base) {
def digits = "0123456789abcdefghijklmnopqrstuvqxyz"
var val := 0
for (str) do {c->
def n = c.ord
val := val * base
var inc := 0
if ((n >= 48) && (n <= 57)) then {
inc := n - 48 // 0
} else {
inc := n - 87 // 'a' - 10
}
if (inc >= base) then {
util.syntax_error("no such digit '{c}' in base {base}")
}
val := val + inc
}
val
}
method makeNumToken(accum) {
var base := 10
var sofar := ""
for (accum) do {c->
if (c == "x") then {
base := sofar.asNumber
if (base == 0) then {
base := 16
}
sofar := ""
} else {
sofar := sofar ++ c
}
}
NumToken.new(fromBase(sofar, base).asString)
}
// True if ov is a valid identifier character. Identifier
// characters are Unicode letters, Unicode numbers, apostrophe,
// and (currently) underscore.
method isidentifierchar(ov) {
if (unicode.isLetter(ov) || unicode.isNumber(ov)
|| (ov == 95) || (ov == 39)) then {
// 95 is _, 39 is '
true
} else {
false
}
}
// True if c (with codepoint ordval) is a valid operator character.
method isoperatorchar(c, ordval) {
var ret := false
if ((c == "-") || (c == "&") || (c == "||") || (c == ":")
|| (c == "%") || (c == "^")
|| (c == "*") || (c == "/") || (c == "+") || (c == "!")
) then {
ret := true
} elseif (unicode.isSymbolMathematical(ordval)) then {
ret := true
}
ret
}
// Read the program text from util.infile and return a list of
// tokens.
method lexfile(file) {
util.log_verbose("reading source.")
lexinput(file.read)
}
method lexinput(input) {
var tokens := []
var mode := "n"
var newmode := mode
var instr := false
var inBackticks := false
var backtickIdent := false
var accum := ""
var escaped := false
var prev := ""
var unichars := 0
var codepoint := 0
var interpdepth := 0
var interpString := false
var atStart := true
var cline := ""
var lineStr := ""
linePosition := 0
util.log_verbose("lexing.")
for (input) do { c ->
linePosition := linePosition + 1
util.setPosition(lineNumber, linePosition)
var ct := ""
var ordval := c.ord // String.ord gives the codepoint
if ((unicode.isSeparator(ordval) && (ordval != 32) &&
(ordval != 8232)) || (ordval == 9)) then {
// Character is whitespace, but not an ASCII space or
// Unicode LINE SEPARATOR, or is a tab
util.syntax_error("illegal whitespace in input: "
++ "{ordval}, {unicode.name(c)}")
}
if (unicode.isControl(ordval) && (ordval != 10)
&& (ordval != 13)) then {
// Character is a control character other than
// carriage return or line feed.
util.syntax_error("illegal control character in "
++ "input: #{ordval} on line {lineNumber}"
++ " character {linePosition}.")
}
if (atStart && (linePosition == 1)) then {
if (c == "#") then {
mode := "p"
newmode := mode
} else {
atStart := false
}
}
if (instr || inBackticks) then {
} elseif ((mode != "c") && (mode != "p")) then {
// Not in a comment, so look for a mode.
if ((c == " ") && (mode != "d")) then {
newmode := "n"
}
if (c == "\"") then {
// Beginning of a string
newmode := "\""
instr := true
if (prev == "x") then {
// Or, actually of an Octet literal
newmode := "x"
mode := "n"
}
}
if (c == "`") then {
newmode := "I"
inBackticks := true
}
ct := isidentifierchar(ordval)
if (ct) then {
newmode := "i"
}
ct := ((ordval >= 48) && (ordval <=57))
if (ct && (mode != "i")) then {
newmode := "m"
}
if ((ordval >= 97) && (ordval <=122) && (mode == "m")) then {
newmode := "m"
}
if ((mode == "i") && (c == "<")) then {
newmode := "<"
} elseif (((mode == "i") || (mode == ">")
|| (mode == "<"))
&& (c == ">")) then {
if (mode == ">") then {
modechange(tokens, mode, accum)
}
newmode := ">"
} elseif (isoperatorchar(c, ordval)) then {
newmode := "o"
}
if ((c == "(") || (c == ")") || (c == ",") || (c == ".")
|| (c == "\{") || (c == "}") || (c == "[")
|| (c == "]") || (c == ";")) then {
newmode := c
}
if ((c == "#") && (mode != "p")) then {
util.syntax_error("illegal operator character"
++ ": #{ordval}"
++ " '{c}', {unicode.name(c)}")
}
if ((c == ".") && (accum == ".")) then {
// Special handler for .. operator
mode := "o"
newmode := mode
}
if ((c == "/") && (accum == "/")) then {
// Start of comment
mode := "c"
newmode := mode
}
if ((newmode == mode) && (mode == "n")
&& (unicode.isSeparator(ordval).not)
&& (unicode.isControl(ordval).not)) then {
if ((unicode.isSeparator(ordval).not)
&& (ordval != 10) && (ordval != 13)
&& (ordval != 32)) then {
util.syntax_error("unknown character in "
++ "input: #{ordval}"
++ " '{c}', {unicode.name(c)}")
}
}
if ((c == ".") && (accum == "..")) then {
// Special handler for ... identifier
mode := "n"
newmode := mode
modechange(tokens, "i", "...")
accum := ""
}
}
if ((mode == "x") && (c == "\"") && (escaped.not)) then {
// End of octet literal
newmode := "n"
instr := false
}
if ((mode == "\"") && (c == "\"") && (escaped.not)) then {
// End of string literal
newmode := "n"
instr := false
if (interpString) then {
modechange(tokens, mode, accum)
modechange(tokens, ")", ")")
mode := newmode
interpString := false
}
}
if ((mode == "I") && (inBackticks) && (c == "`")) then {
// End of backticked identifier
newmode := "n"
inBackticks := false
backtickIdent := true
}
if (newmode != mode) then {
// This character is the beginning of a different
// lexical mode - process the old one now.
modechange(tokens, mode, accum)
if ((newmode == "}") && (interpdepth > 0)) then {
modechange(tokens, ")", ")")
modechange(tokens, "o", "++")
newmode := "\""
instr := true
interpdepth := interpdepth - 1
}
mode := newmode
if (instr || inBackticks) then {
// String accum should skip the opening quote, but
// other modes' should include their first
// character.
accum := ""
} else {
accum := c
}
if ((mode == "(") || (mode == ")") || (mode == "[")
|| (mode == "]") || (mode == "\{")
|| (mode == "}")) then {
modechange(tokens, mode, accum)
mode := "n"
newmode := "n"
accum := ""
}
backtickIdent := false
} elseif (instr) then {
if (c == "\n") then {
if (interpdepth > 0) then {
util.syntax_error("Runaway string "
++ "interpolation")
} else {
util.syntax_error("Newlines not permitted "
++ "in string literals")
}
}
if (escaped) then {
if (c == "n") then {
// Newline escape
accum := accum ++ "\u000a"
} elseif (c == "u") then {
// Beginning of a four-digit Unicode escape
// (for a BMP codepoint).
unichars := 4
codepoint := 0
} elseif (c == "U") then {
// Beginning of a six-digit Unicode escape
// (for a general codepoint).
unichars := 6
codepoint := 0
} elseif (c == "t") then {
// Tab escape
accum := accum ++ "\u0009"
} elseif (c == "r") then {
// Carriage return escape
accum := accum ++ "\u000d"
} elseif (c == "b") then {
// Backspace escape
accum := accum ++ "\u0008"
} elseif (c == "l") then {
// LINE SEPARATOR escape
accum := accum ++ "\u2028"
} elseif (c == "f") then {
// Form feed/"page down" escape
accum := accum ++ "\u000c"
} elseif (c == "e") then {
// Escape escape
accum := accum ++ "\u001b"
} else {
// For any other character preceded by \,
// insert it literally.
accum := accum ++ c
}
escaped := false
} elseif (c == "\\") then {
// Begin an escape sequence
escaped := true
} elseif (unichars > 0) then {
// There are still hex digits to read for a
// Unicode escape. Use the current character
// as a hex digit and update the codepoint
// being calculated with its value.
unichars := unichars - 1
codepoint := codepoint * 16
codepoint := codepoint + hexdecchar(c)
if (unichars == 0) then {
// At the end of the sequence construct
// the character in the unicode library.
accum := accum ++ unicode.create(codepoint)
}
} elseif (c == "\{") then {
if (interpString.not) then {
modechange(tokens, "(", "(")
interpString := true
}
modechange(tokens, mode, accum)
modechange(tokens, "o", "++")
modechange(tokens, "(", "(")
mode := "n"
newmode := "n"
accum := ""
instr := false
interpdepth := interpdepth + 1
} else {
accum := accum ++ c
}
} elseif (inBackticks) then {
if (c == "\n") then {
util.syntax_error("Newlines not permitted in"
++ "backtick identifiers")
}
accum := accum ++ c
} elseif ((c == "\n") || (c == "\r")) then {
// Linebreaks terminate any open tokens
modechange(tokens, mode, accum)
mode := "d"
newmode := "d"
accum := ""
if (c != "\r") then {
cLines.push(cline)
cline := ""
lines.push(lineStr)
lineStr := ""
}
} else {
accum := accum ++ c
}
if ((accum == "...") && {mode == "o"}) then {
modechange(tokens, "i", "...")
newmode := "n"
mode := newmode
accum := ""
}
if (c == "\n") then {
// Linebreaks increment the line counter and insert a
// special "line" token, which the parser can use to
// track the origin of AST nodes for later error
// reporting.
lineNumber := lineNumber + 1
linePosition := 0
startPosition := 1
util.setPosition(lineNumber, 0)
} elseif (c == "\r") then {
} else {
if (c == "\"") then {
cline := cline ++ "\\\""
} else {
if (c == "\\") then {
cline := cline ++ "\\\\"
} else {
cline := cline ++ c
}
}
lineStr := lineStr ++ c
}
prev := c
}
modechange(tokens, mode, accum)
util.cLines := cLines
util.lines := lines
tokens
}
}
}
}
method Lexer {
LexerClass
}