// Called recursively to generate tokens/instructions from a source code string
public static IEnumerable<string> Parse(string source, ref int sourceI, GrammarElement element, ParseContext context)
{
IEnumerable<string> res = null;
if (element is GrammarElementA) {
var elA = element as GrammarElementA;
int iter = sourceI;
using (var level = context.GetCurrentContext()) {
for (int e = 0; e < elA.Elements.Length; ++e) {
var ok = Parse(source, ref iter, elA.Elements[e], context);
if (ok == null) {
level.RemoveChanges();
return null;
}
if (res == null) res = ok; else res = res.Concat(ok);
}
}
sourceI = iter;
} else if (element is GrammarElementO) {
var elA = element as GrammarElementO;
for (int e = 0; e < elA.Elements.Length; ++e) {
int iter = sourceI;
var ok = Parse(source, ref iter, elA.Elements[e], context);
if (ok != null) { sourceI = iter; res = ok; break; }
}
} else if (element is GrammarElementT) {
ParserUtil.IteratePastWhitespaceAndComments(source, ref sourceI);
var elA = element as GrammarElementT;
var token = elA.TokenType;
int match = token.Match(source, sourceI);
if (match < 0) {
context.MarkError(sourceI, token);
return null;
}
sourceI += match;
return new string[] { token.Name };
} else if (element is GrammarElementR) {
var elA = element as GrammarElementR;
var rule = elA.Rule;
ParserUtil.IteratePastWhitespaceAndComments(source, ref sourceI);
int sourceS = sourceI;
int iter = sourceI;
bool isImplicit = rule.Name == "Implicit";
isImplicit = false;
ParseContext.Level level = new ParseContext.Level();
if (!isImplicit) {
context.PushRule(rule);
level = context.GetCurrentContext();
}
for (int r = 1; r <= rule.Cardinality.To; ++r) {
if (!isImplicit) level.ClearChildren();
var ok = Parse(source, ref iter, rule.Element, context);
if (ok != null) {
if (!isImplicit) {
if (rule.Build != null) {
SourceIterator sourceIter = new SourceIterator(source, sourceI, iter);
rule.Build(level, sourceIter);
} else {
level.PassThrough();
}
}
if (r >= rule.Cardinality.From) {
if (res == null) res = ok; else res = res.Concat(ok);
sourceI = iter;
}
} else break;
}
if (res == null && rule.Cardinality.From == 0) {
res = new string[] { };
}
if (!isImplicit) {
context.PopRule(rule);
if (res == null) level.RemoveChanges();
level.Dispose();
}
}
return res;
}
public Level(ParseContext context, int level) {
Context = context;
Index = level;
oldStoreStart = Context.GetStoreAt(Index).Count;
oldChildStart = Context.GetStoreAt(Index + 1).Count;
}
public static InstructionInstance[] Parse(string source, Action<string, ErrorLevelE, int> onError)
{
int iter = 0;
ParseContext context = new ParseContext();
// Try to parse the code into rough tokens/instructions
var res = Parse(source, ref iter, ParserSetup.BlockRule, context);
ParserUtil.IteratePastWhitespaceAndComments(source, ref iter);
// Was there more code that couldnt be parsed?
if (res == null || iter < source.Length) {
int line = source.Substring(0, context.MaxParseChar).Count(c => c == '\n') + 1;
string lineData = null;
int at = context.MaxParseChar;
while (at > 0 && source[at - 1] != '\n') --at;
int end = source.IndexOf('\n', at);
while (end > 0 && char.IsWhiteSpace(source[end - 1])) --end;
while (at < end && char.IsWhiteSpace(source[at])) ++at;
if (end == -1) end = source.Length;
lineData = source.Substring(at, end - at);
onError(
"Unable to parse XScript at line " + line + " byte " + context.MaxParseChar + "\r\n" +
" " + lineData + "\r\n" +
" " + new string(Enumerable.Repeat(' ', context.MaxParseChar - at).ToArray()) + "^\r\n" +
"Expected:\r\n" +
context.ExpectedTokens.Select(k => " As <" + k.Key.ToString() + ">:\r\n" +
"\t" + k.Value.Select(v => v.ToString()).Aggregate((s1, s2) => s1 + ", " + s2) + "\r\n"
).Aggregate((s1, s2) => s1 + s2),
ErrorLevelE.Error,
line
);
}
// Ensure no temporary instructions are still present (starting with '+')
var parsedInstrs = context.GetCurrentContext().Children;
for (int i = 0; i < parsedInstrs.Count; ++i) {
var instr = parsedInstrs[i];
if (instr.Command.StartsWith("+")) {
switch (instr.Command) {
case "+Error": onError((string)instr.Value, ErrorLevelE.Error, instr.Location.GetLineNumber(source)); break;
case "+Info": onError((string)instr.Value, ErrorLevelE.Info, instr.Location.GetLineNumber(source)); break;
case "+Warning": onError((string)instr.Value, ErrorLevelE.Warning, instr.Location.GetLineNumber(source)); break;
default: {
onError("Unexpected token " + instr.Command, ErrorLevelE.Error, instr.Location.GetLineNumber(source));
} break;
}
}
}
// Begin matching internal instructions to tokens/instructions extracted
// from the source string
List<InstructionInstance> instrList = new List<InstructionInstance>();
{
var instrSet = StackBasedVM.Instructions.Set;
List<StackType> stack = new List<StackType>();
// Helper method to insert instructions into the instrList array
// without putting them at the end
Action<int, InstructionInstance> insertInstruction = (at, instr) => {
instrList.Insert(at, instr);
for (int s = 0; s < stack.Count; ++s) {
if (stack[s].InstructionId >= at) {
var stackT = stack[s];
stackT.InstructionId++;
stack[s] = stackT;
}
}
};
// Where to read instructions from
for (int i = 0; i < parsedInstrs.Count; ++i) {
var instr = parsedInstrs[i];
// We get the instruction which best matches the parameters
// available on the stack, when the instruction is invoked
// (for type safety)
Instruction bestInstr = null;
int bestScore = 0;
foreach (var iSet in instrSet) {
var instrP = iSet.Value;
// Must match names
if (instrP.Name != instr.Command) continue;
// Calculate a score for how well the parameters match
int score = 100;
for (int p = 0; p < instrP.ConsumptionValues.Length; ++p) {
string paramType = instrP.ConsumptionValues[p];
string stackType = stack[stack.Count - 1 - p].Type;
score = score * ParserUtil.CompareConversion(stackType, paramType) / 100;
if (score <= bestScore) break;
}
// Is this score better than our previous score?
if (score <= bestScore) continue;
bestScore = score;
bestInstr = instrP;
}
// No instruction was found for this token/instruction
if (bestInstr == null) {
onError("Unable to find instruction for " + instr + "\r\n" +
(bestInstr != null ?
" Best match expected (" + bestInstr.ConsumptionValues.Aggregate((s1, s2) => s1 + ", " + s2) +
") but was given (" + stack.Skip(stack.Count - bestInstr.ConsumptionValues.Length).Select(v => v.Type).Aggregate((s1, s2) => s1 + ", " + s2) + ")"
:
" Using params (" + stack.Skip(Math.Max(stack.Count - 3, 0)).Select(v => v.Type).Aggregate((s1, s2) => s1 + ", " + s2) + ")"
),
ErrorLevelE.Error,
instr.Location.GetLineNumber(source)
);
break;
} else {
// Are any of the parameters available on the stack incorrect?
// Do they need to be cast to anoter type? (ie. float to int)
for (int p = 0; p < bestInstr.ConsumptionValues.Length; ++p) {
var stackT = stack[stack.Count - 1 - p];
var toConvInstr = instrList[stackT.InstructionId];
string paramType = bestInstr.ConsumptionValues[p];
string stackType = stackT.Type;
if (paramType == stackType) continue;
if (ParserUtil.StripStars(paramType) == "var") continue;
// Constants can be changed at compile-time
if (toConvInstr.Instruction.Name == "Constant") {
string type = ParserUtil.GetCleanTypeName(toConvInstr.Data.GetType().Name);
Debug.Assert(stackT.Type == type,
"Stack type and constant value type must match!");
if (paramType == "int") {
toConvInstr.Data = Convert.ToInt32(toConvInstr.Data);
continue;
} else if (paramType == "real") {
toConvInstr.Data = (XReal)Convert.ToSingle(toConvInstr.Data);
continue;
}
}
// Otherwise fall back to the more expensive run-time conversion
int score = ParserUtil.CompareConversion(stackType, paramType);
if (score < 100) {
var convInstr = instrSet.FirstOrDefault(i2 => i2.Value.Type == paramType && i2.Value.Name == "Conform").Value;
if (convInstr == null) {
onError("Unable to find conversion from " + stackType + " to " + paramType,
ErrorLevelE.Warning,
instr.Location.GetLineNumber(source));
continue;
}
insertInstruction(stackT.InstructionId + 1, new InstructionInstance() {
Instruction = convInstr,
Data = stackType + "2" + paramType
});
}
}
// Simulate executing the instruction to maintain our
// faux stack, so next instructions can get the correct
// instruction for the expected types
Debug.Assert(bestInstr != null,
"Unable to find matching instruction!");
int toRemove = bestInstr.ConsumptionValues.Length;
string retVal = bestInstr.ReturnValues.Length > 0 ? bestInstr.ReturnValues[0] : "void";
int retStars = ParserUtil.CountStars(retVal);
if (retStars > 0) retVal = retVal.Substring(0, retVal.Length - retStars);
if (retVal == "var") {
retVal = ParserUtil.StripStars(instr.Type);
if (retVal == "auto") retVal = "var";
}
if (retVal == "var" && toRemove > 0)
retVal = ParserUtil.StripStars(stack[stack.Count - 1].Type);
else if (retStars > 0) retVal = ParserUtil.AddStars(retVal, retStars);
if (toRemove > 0) stack.RemoveRange(stack.Count - toRemove, toRemove);
if (retVal != "void") stack.Add(new StackType(instrList.Count, retVal));
instrList.Add(new InstructionInstance() {
Instruction = bestInstr,
Data = instr.Value,
});
}
}
Debug.Assert(stack.Count == 0,
"Stack is not balanced!");
}
// Our parser wraps the entire file in a block, remove this block
// so that global variables are not cleaned up after execution
if(instrList.Count > 0) {
Debug.Assert(instrList[0].Instruction.Name == "BlockStart",
"Script should be contained within a block");
Debug.Assert(instrList[instrList.Count - 1].Instruction.Name == "BlockEnd",
"Script should be contained within a block");
instrList.RemoveAt(0);
instrList.RemoveAt(instrList.Count - 1);
}
return instrList.ToArray();
//context.BreakOnError = true;
//res = Parse(str, ref iter, blockRule, context);
}
