static string BuildErrorMessages(ParseContext context)
{
var newLine = Environment.NewLine;
var text = new StringBuilder();
var textLength = context.BaseText.Length;
if (context.ErrorCount > 1)
text.Append(newLine);
for (var i = 0; i < context.ErrorCount; ++i) {
var token = context.GetError(i);
if (i > 0)
text.Append(newLine);
if (context.ErrorCount > 1)
text.Append(' ');
var found = context.BaseText.Substring(token.Offset);
// Truncate the "found" text before the start of the next error
if (i + 1 < context.ErrorCount) {
var nextError = context.GetError(i + 1);
var length = nextError.Offset - token.Offset;
if (found.Length > length)
found = found.Substring(0, length);
}
if (found.Length > 0) {
text.Append("Expected " + context.Expected + " but found "
+ Truncate(found) + " when matching " + GetConstructName(token.GrammarConstruct));
}
else if (token.Offset + found.Length >= textLength) {
text.Append("Expected " + context.Expected
+ " but reached end of input when matching " + GetConstructName(token.GrammarConstruct));
}
else {
text.Append("Expected " + context.Expected
+ " but was missing when matching " + GetConstructName(token.GrammarConstruct));
}
}
return text.ToString();
}
