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Les3.cs
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Les3.cs
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// Currently, no IntelliSense (code completion) is available in .ecs files,
// so it can be useful to split your Lexer and Parser classes between two
// files. In this file (the .cs file) IntelliSense will be available and
// the other file (the .ecs file) contains your grammar code.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Diagnostics;
using System.Numerics;
using System.ComponentModel;
using Loyc; // optional (for IMessageSink, Symbol, etc.)
using Loyc.Collections; // optional (many handy interfaces & classes)
using Loyc.Syntax.Lexing; // For BaseLexer
using Loyc.Syntax; // For BaseParser<Token> and LNode
using Loyc.Collections.Impl;
using S = Loyc.Syntax.CodeSymbols;
namespace Loyc.Syntax.Les
{
[EditorBrowsable(EditorBrowsableState.Never)] // external code shouldn't use this class, except the syntax highlighter
public partial class Les3Lexer : BaseILexer<ICharSource, Token>, ILexer<Token>
{
// When using the Loyc libraries, `BaseLexer` and `BaseILexer` read character
// data from an `ICharSource`, which the string wrapper `UString` implements.
public Les3Lexer(string text, string fileName = "")
: this((UString)text, fileName, BaseLexer.LogExceptionErrorSink) { }
public Les3Lexer(ICharSource text, string fileName, IMessageSink sink, int startPosition = 0)
: base(text, fileName, startPosition) { ErrorSink = sink; }
/// <summary>If this flag is true, all literals except plain strings and
/// true/false/null are stored as CustomLiteral, bypassing number parsing
/// so that all original characters are preserved if the output is written
/// back to text.</summary>
public bool PreferCustomLiterals { get; set; }
/// <summary>Used for syntax highlighting, which doesn't care about token values.
/// This option causes the Token.Value to be set to a default, like '\0' for
/// single-quoted strings and 0 for numbers. Operator names are still parsed.</summary>
bool SkipValueParsing { get; set; }
protected TokenType _type; // predicted type of the current token
protected NodeStyle _style; // indicates triple-quoted string, hex or binary literal
protected int _startPosition;
// Helps filter out newlines that are not directly inside braces or at the top level.
InternalList<TokenType> _brackStack = new InternalList<TokenType>(
new TokenType[8] { TokenType.LBrace, 0,0,0,0,0,0,0 }, 1);
// Gets the text of the current token that has been parsed so far
protected UString Text()
{
return CharSource.Slice(_startPosition, InputPosition - _startPosition);
}
protected sealed override void AfterNewline() // sealed to avoid virtual call
{
base.AfterNewline();
}
protected override bool SupportDotIndents() { return true; }
object ParseLiteral2(UString typeMarker, UString parsedText, bool isNumericLiteral)
{
if (SkipValueParsing)
return null;
if (PreferCustomLiterals)
return new CustomLiteral(parsedText.ToString(), (Symbol)typeMarker.ToString());
else {
string syntaxError;
var result = ParseLiteral(typeMarker, parsedText, isNumericLiteral, out syntaxError);
if (syntaxError != null) {
var pos = new SourceRange(SourceFile, _startPosition, InputPosition - _startPosition);
ErrorSink.Write(Severity.Error, pos, syntaxError);
}
return result;
}
}
public static object ParseLiteral(UString typeMarker, UString parsedText, bool isNumericLiteral, out string syntaxError)
{
syntaxError = null;
if (typeMarker.Length == 0) {
if (isNumericLiteral) {
// Optimize the most common case: a one-digit integer
if (parsedText.Length == 1) {
Debug.Assert(char.IsDigit(parsedText[0]));
return CG.Cache((int)(parsedText[0] - '0'));
}
typeMarker = "n"; // number
} else {
syntaxError = null;
return parsedText.ToString();
}
}
return ParseNonStringLiteral(typeMarker, parsedText, out syntaxError);
}
protected string ParseStringValue(bool parseNeeded, bool isTripleQuoted)
{
if (SkipValueParsing)
return null;
string value;
if (parseNeeded) {
UString original = CharSource.Slice(_startPosition, InputPosition - _startPosition);
value = Les2Lexer.UnescapeQuotedString(ref original, Error, IndentString, true);
Debug.Assert(original.IsEmpty);
} else {
Debug.Assert(CharSource.TryGet(InputPosition - 1, '?') == CharSource.TryGet(_startPosition, '!'));
if (isTripleQuoted)
value = CharSource.Slice(_startPosition + 3, InputPosition - _startPosition - 6).ToString();
else
value = CharSource.Slice(_startPosition + 1, InputPosition - _startPosition - 2).ToString();
}
return value;
}
protected object ParseSQStringValue(bool parseNeeded)
{
if (SkipValueParsing)
return null;
else {
var text = Text();
if (!parseNeeded && text.Length == 3)
return text[1];
else {
var value = Les2Lexer.ParseSQStringValue(text, Error);
if (value is string)
return new CustomLiteral(value, (Symbol)"char");
return value;
}
}
}
protected static Dictionary<UString, Func<UString, object>> LiteralParsers = InitLiteralParsers();
protected static Dictionary<UString, Func<UString, object>> InitLiteralParsers()
{
var dict = new Dictionary<UString, Func<UString, object>>();
Func<UString, object> i32 = s => { long n; return ParseSigned(s, out n) && (int)n == n ? (object)(int)n : null; };
Func<UString, object> u32 = s => { long n; return ParseSigned(s, out n) && (uint)n == n ? (object)(uint)n : null; };
Func<UString, object> i64 = s => { long n; return ParseSigned(s, out n) ? (object)(long)n : null; };
Func<UString, object> u64 = s => { ulong n; return ParseULong(s, out n) ? (object)(ulong)n : null; };
Func<UString, object> u = s => { ulong n; return ParseULong(s, out n) ? ((uint)n == n ? (object)(uint)n : (object)(ulong)n) : null; };
Func<UString, object> big = s => { BigInteger n; return ParseBigInt(s, out n) ? (object)n : null; };
Func<UString, object> f32 = s => { double n; return ParseDouble(s, out n) && n >= float.MinValue && n <= float.MaxValue ? (object)(float)n : null; };
Func<UString, object> f64 = s => { double n; return ParseDouble(s, out n) ? (object)n : null; };
Func<UString, object> dec = s => {
// TODO: support decimal properly
long n;
double d;
if (ParseSigned(s, out n))
return (decimal)n;
if (ParseDouble(s, out d))
return (decimal)d;
return null;
};
dict["u32"] = u32;
dict["i32"] = i32;
dict["u64"] = dict["ul"] = dict["uL"] = dict["UL"] = dict["Ul"] = u64;
dict["u"] = dict["U"] = u;
dict["i64"] = dict["l"] = dict["L"] = i64;
dict["f32"] = dict["f"] = dict["F"] = f32;
dict["f64"] = dict["d"] = dict["D"] = f64;
dict["m"] = dec;
dict["z"] = big;
dict["s"] = s => (Symbol)s;
dict["re"] = s => {
try { return new System.Text.RegularExpressions.Regex((string)s); }
catch { return new CustomLiteral(s, (Symbol)"re"); }
};
dict["n"] = GeneralNumberParser;
dict["@@"] = ParseSingletonLiteral;
return dict;
}
static object GeneralNumberParser(UString s)
{
long n;
BigInteger z;
double d;
if (ParseSigned(s, out n)) {
if ((int)n == n)
return (int)n;
else if ((uint)n == n)
return (uint)n;
else
return n;
} else if (s.Length >= 18 && ParseBigInt(s, out z)) {
// (The length check is an optimization: the shortest number that
// does not fit in a long is 0x8000000000000000.)
if (z >= 0 && z <= UInt64.MaxValue)
return (ulong)z;
return z;
} else if (ParseDouble(s, out d)) {
return d;
} else
return null;
}
static bool ParseSigned(UString s, out long n)
{
n = 0;
bool negative;
int radix = GetSignAndRadix(ref s, out negative);
if (radix == 0)
return false;
var flags = ParseNumberFlag.SkipSingleQuotes | ParseNumberFlag.SkipUnderscores | ParseNumberFlag.StopBeforeOverflow;
ulong u;
if (ParseHelpers.TryParseUInt(ref s, out u, radix, flags) && s.Length == 0) {
n = negative ? -(long)u : (long)u;
return (long)u >= 0;
}
return false;
}
static bool ParseBigInt(UString s, out BigInteger n)
{
n = BigInteger.Zero;
bool negative;
int radix = GetSignAndRadix(ref s, out negative);
if (radix == 0)
return false;
var flags = ParseNumberFlag.SkipSingleQuotes | ParseNumberFlag.SkipUnderscores | ParseNumberFlag.StopBeforeOverflow;
if (ParseHelpers.TryParseUInt(ref s, out n, radix, flags) && s.Length == 0) {
if (negative) n = -n;
return true;
}
return false;
}
static bool ParseULong(UString s, out ulong u)
{
u = 0;
bool negative;
int radix = GetSignAndRadix(ref s, out negative);
if (radix == 0 || negative)
return false;
var flags = ParseNumberFlag.SkipSingleQuotes | ParseNumberFlag.SkipUnderscores | ParseNumberFlag.StopBeforeOverflow;
return ParseHelpers.TryParseUInt(ref s, out u, radix, flags) && s.Length == 0;
}
private static bool ParseDouble(UString s, out double d)
{
d = double.NaN;
bool negative;
int radix = GetSignAndRadix(ref s, out negative);
if (radix == 0)
return false;
var flags = ParseNumberFlag.SkipSingleQuotes | ParseNumberFlag.SkipUnderscores | ParseNumberFlag.StopBeforeOverflow;
d = ParseHelpers.TryParseDouble(ref s, radix, flags);
if (negative) d = -d;
return !double.IsNaN(d) && s.Length == 0;
}
static int GetSignAndRadix(ref UString s, out bool negative)
{
negative = false;
if (s.Length == 0)
return 0;
char s0 = s[0];
if (s0 == '-' || s0 == '\x2212') {
negative = true;
s = s.Slice(1);
if (s.Length == 0)
return 0;
}
int radix = 10;
if (s[0] == '0') {
var x = s[1, '\0'];
if ((radix = x == 'x' ? 16 : x == 'b' ? 2 : 10) != 10) {
s = s.Substring(2);
if (s.Length == 0)
return 0;
}
}
return radix;
}
private static object ParseNonStringLiteral(UString typeMarker, UString parsedText, out string syntaxError)
{
syntaxError = null;
Func<UString, object> parser;
object value = null;
if (LiteralParsers.TryGetValue(typeMarker, out parser)) {
value = parser(parsedText);
if (value == null)
syntaxError = "Syntax error in '{typeMarker}' literal".Localized("typeMarker", typeMarker);
}
return value ?? new CustomLiteral(parsedText.ToString(), (Symbol)typeMarker.ToString());
}
protected static readonly Symbol _AtAt = GSymbol.Get("@@");
#region Singleton literals (e.g. @@-inf.f)
internal static Dictionary<UString, object> NamedLiterals = new Dictionary<UString, object>()
{
{ "true", G.BoxedTrue },
{ "false", G.BoxedFalse },
{ "null", null },
{ "void", @void.Value },
{ "nan.f", float.NaN },
{ "nan.d", double.NaN },
{ "inf.f", float.PositiveInfinity },
{ "inf.d", double.PositiveInfinity },
{ "-inf.f", float.NegativeInfinity },
{ "-inf.d", double.NegativeInfinity }
};
private object ParseAtAtLiteral(UString text)
{
Debug.Assert(text.StartsWith("@@"));
text = text.Substring(2);
if (PreferCustomLiterals)
return new CustomLiteral(CG.Cache(text.ToString()), _AtAt);
return ParseSingletonLiteral(text);
}
static object ParseSingletonLiteral(UString text)
{
object value;
if (NamedLiterals.TryGetValue(text, out value))
return value;
return new CustomLiteral(CG.Cache(text.ToString()), _AtAt);
}
#endregion
#region Operator parsing
protected Dictionary<UString, Pair<Symbol, TokenType>> _opCache = new Dictionary<UString, Pair<Symbol, TokenType>>();
protected Symbol ParseOp(out TokenType type)
{
UString opText = Text();
Pair<Symbol, TokenType> symAndType;
if (!_opCache.TryGetValue(opText, out symAndType))
_opCache[opText] = symAndType = GetOpNameAndType(opText);
type = symAndType.B;
return symAndType.A;
}
private Pair<Symbol, TokenType> GetOpNameAndType(UString op)
{
Debug.Assert(op.Length > 0);
TokenType tt;
Symbol name;
int length = op.Length;
// Get first and last of the operator's initial punctuation
char first = op[0], last = op[length - 1];
if (length == 1) {
if (first == '!')
return Pair.Create(CodeSymbols.Not, TokenType.Not);
if (first == ':')
return Pair.Create(CodeSymbols.Colon, TokenType.Colon);
}
Debug.Assert(first != '\'');
name = (Symbol)("'" + op);
if (name == CodeSymbols.Dot)
return Pair.Create(name, TokenType.Dot);
if (length >= 2 && first == last && (last == '+' || last == '-' || last == '!'))
tt = TokenType.PreOrSufOp;
else if (first == '$')
tt = TokenType.PrefixOp;
else if (last == '.' && (length == 1 || first != '.'))
tt = TokenType.Dot;
else if (last == '=' && (length == 1 || (first != '=' && first != '!' && !(length == 2 && (first == '<' || first == '>')))))
tt = TokenType.Assignment;
else
tt = TokenType.NormalOp;
return Pair.Create(name, tt);
}
#endregion
void PrintErrorIfTypeMarkerIsKeywordLiteral(object boolOrNull)
{
if (boolOrNull != NoValue.Value)
ErrorSink.Write(Severity.Error, IndexToPositionObject(_startPosition), "Keyword '{0}' used as a type marker", boolOrNull);
}
}
[EditorBrowsable(EditorBrowsableState.Never)] // used only by syntax highlighter
public partial class Les3Parser : BaseParserForList<Token, int>
{
LNodeFactory F;
public Les3Parser(IList<Token> list, ISourceFile file, IMessageSink sink, int startIndex = 0)
: base(list, default(Token), file, startIndex) { ErrorSink = sink; }
public void Reset(IList<Token> list, ISourceFile file, int startIndex = 0)
{
Reset(list, default(Token), file, startIndex);
}
protected override void Reset(IList<Token> list, Token eofToken, ISourceFile file, int startIndex = 0)
{
CheckParam.IsNotNull("file", file);
base.Reset(list, eofToken, file, startIndex);
F = new LNodeFactory(file);
}
/// <summary>Top-level rule: expects a sequence of statements followed by EOF</summary>
/// <param name="separator">If there are multiple expressions, the Value of
/// this Holder is set to the separator between them: Comma or Semicolon.</param>
public IEnumerable<LNode> Start(Holder<TokenType> separator)
{
foreach (var stmt in ExprListLazy(separator))
yield return stmt;
Match((int) EOF, (int) separator.Value);
}
// Method required by base class for error messages
protected override string ToString(int type)
{
switch ((TokenType)type) {
case TokenType.LParen: return "'('";
case TokenType.RParen: return "')'";
case TokenType.LBrack: return "'['";
case TokenType.RBrack: return "']'";
case TokenType.LBrace: return "'{'";
case TokenType.RBrace: return "'}'";
case TokenType.Comma: return "','";
case TokenType.Semicolon: return "';'";
}
return ((TokenType)type).ToString().Localized();
}
// This is virtual so that a syntax highlighter can easily override and colorize it
protected virtual LNode MarkSpecial(LNode n)
{
return n.SetBaseStyle(NodeStyle.Special);
}
// This is virtual so that a syntax highlighter can easily override and colorize it
protected virtual LNode MarkCall(LNode n)
{
return n.SetBaseStyle(NodeStyle.PrefixNotation);
}
protected LNode MissingExpr(Token tok, string error = null, bool afterToken = false)
{
int startIndex = afterToken ? tok.EndIndex : tok.StartIndex;
LNode missing = F.Id(S.Missing, startIndex, tok.EndIndex);
if (error != null)
ErrorSink.Write(Severity.Error, missing.Range, error);
return missing;
}
protected Les3PrecedenceMap _prec = Les3PrecedenceMap.Default;
protected Precedence PrefixPrecedenceOf(Token t)
{
var prec = _prec.Find(OperatorShape.Prefix, t.Value);
if (prec == LesPrecedence.Other)
ErrorSink.Write(Severity.Error, F.Id(t),
"Operator `{0}` cannot be used as a prefix operator", t.Value);
return prec;
}
// Note: continuators cannot be used as binary operator names
internal static readonly HashSet<Symbol> ContinuatorOps = new HashSet<Symbol> {
(Symbol)"#else", (Symbol)"#elsif", (Symbol)"#elseif",
(Symbol)"#catch", (Symbol)"#except", (Symbol)"#finally",
(Symbol)"#while", (Symbol)"#until",
(Symbol)"#plus", (Symbol)"#using",
};
internal static readonly Dictionary<object, Symbol> Continuators =
ContinuatorOps.ToDictionary(kw => (object)(Symbol)kw.Name.Substring(1), kw => kw);
bool CanParse(Precedence context, int li, out Precedence prec)
{
var opTok = LT(li);
if (opTok.Type() == TokenType.Id) {
var opTok2 = LT(li + 1);
if (opTok2.Type() == TokenType.NormalOp && opTok.EndIndex == opTok2.StartIndex)
prec = _prec.Find(OperatorShape.Infix, opTok2.Value);
else {
// Oops, LesPrecedenceMap doesn't yet support non-single-quote ops
// (bacause it's shared with LESv2 which doesn't have them)
// TODO: improve performance by avoiding this concat
prec = _prec.Find(OperatorShape.Infix, (Symbol)("'" + opTok.Value.ToString()));
}
} else
prec = _prec.Find(OperatorShape.Infix, opTok.Value);
bool result = context.CanParse(prec);
if (!context.CanMixWith(prec))
Error(li, "Operator \"{0}\" cannot be mixed with the infix operator to its left. Add parentheses to clarify the code's meaning.", LT(li).Value);
return result;
}
}
}