Ast.Variant _GetVariant(FtlParserStream ps, bool hasDefault)
{
bool defaultIndex = false;
if (ps.CurrentIs('*'))
{
if (hasDefault)
{
throw new ParseException("E0015");
}
ps.Next();
defaultIndex = true;
hasDefault = true;
}
ps.ExpectChar('[');
var key = GetVariantKey(ps);
ps.ExpectChar(']');
if (ps.IsPeekValueStart())
{
ps.SkipIndent();
var value = GetValue(ps);
return(new Ast.Variant(key, value, defaultIndex));
}
throw new ParseException("E0012");
}
Ast.Identifier _GetTermIdentifier(FtlParserStream ps)
{
ps.ExpectChar('-');
var id = this.GetIdentifier(ps);
return(new Ast.Identifier($"-{id.Name}"));
}
Ast.Entry GetEntryOrJunk(FtlParserStream ps)
{
var entryStartPos = ps.GetPosition();
ps.BeginCapture();
try
{
var entry = GetEntry(ps);
ps.ExpectNewLine();
return(entry);
}
catch (ParseException e)
{
var errorPos = ps.GetPosition();
ps.SkipToNextEntryStart();
var nextEntryStart = ps.GetPosition();
// Create a Junk instance
var junk = new Ast.Junk(ps.GetCapturedText());
if (_withSpans)
{
junk.AddSpan(entryStartPos, nextEntryStart);
}
var annot = new Ast.Annotation(e.Code, e.Args, e.Message);
annot.AddSpan(errorPos, errorPos);
junk.AddAnnotation(annot);
return(junk);
}
}
IReadOnlyList <Ast.Variant> GetVariants(FtlParserStream ps)
{
var variants = new List <Ast.Variant>();
bool hasDefault = false;
while (true)
{
ps.ExpectIndent();
var variant = GetVariant(ps, hasDefault);
if (variant.IsDefault)
{
hasDefault = true;
}
variants.Add(variant);
if (!ps.IsPeekNextLineVariantStart())
{
break;
}
}
if (!hasDefault)
{
throw new ParseException("E0010");
}
return(variants);
}
Ast.Entry _GetMessage(FtlParserStream ps)
{
var id = GetIdentifier(ps);
ps.SkipInlineWs();
ps.ExpectChar('=');
Ast.Pattern pattern = null;
if (ps.IsPeekValueStart())
{
ps.SkipIndent();
pattern = GetPattern(ps);
}
else
{
ps.SkipInlineWs();
}
IReadOnlyList <Ast.Attribute> attrs = null;
if (ps.IsPeekNextLineAttributeStart())
{
attrs = GetAttributes(ps);
}
if (pattern == null && attrs == null)
{
throw new ParseException("E0005", id.Name);
}
return(new Ast.Message(id, pattern, attrs));
}
Ast.Entry _GetTerm(FtlParserStream ps)
{
var id = GetTermIdentifier(ps);
ps.SkipInlineWs();
ps.ExpectChar('=');
Ast.SyntaxNode value = null;
if (ps.IsPeekValueStart())
{
ps.SkipIndent();
value = GetValue(ps);
}
else
{
throw new ParseException("E0006", id.Name);
}
IReadOnlyList <Ast.Attribute> attrs = null;
if (ps.IsPeekNextLineAttributeStart())
{
attrs = GetAttributes(ps);
}
return(new Ast.Term(id, value, attrs));
}
Ast.StringLiteral _GetString(FtlParserStream ps)
{
var val = new StringBuilder();
ps.ExpectChar('"');
int ch;
while ((ch = ps.TakeChar(x => x != '"' && x != '\r' && x != '\n')) != Eof)
{
if (ch == '\\')
{
GetEscapeSequence(ps, new int[] { '{', '\\', '"' }, val);
}
else
{
val.Append((char)ch);
}
}
if (ps.CurrentIs('\r') || ps.CurrentIs('\n'))
{
throw new ParseException("E0020");
}
ps.Next();
return(new Ast.StringLiteral(val.ToString()));
}
Ast.SyntaxNode _GetCallArg(FtlParserStream ps)
{
var exp = GetSelectorExpression(ps);
ps.SkipInlineWs();
if (ps.Current != ':')
{
return(exp);
}
var messageReference = exp as Ast.MessageReference;
if (messageReference == null)
{
throw new ParseException("E0009");
}
ps.Next();
ps.SkipInlineWs();
var val = GetArgVal(ps);
return(new Ast.NamedArgument(messageReference.Id, val));
}
public Ast.Resource Parse(TextReader input)
{
var ps = new FtlParserStream(input);
ps.SkipBlankLines();
var entries = new List <Ast.Entry>();
Ast.Comment lastComment = null;
while (ps.Current != Eof)
{
var entry = GetEntryOrJunk(ps);
int blankLines = ps.SkipBlankLines();
// Regular Comments require special logic. Comments may be attached to
// Messages or Terms if they are followed immediately by them. However
// they should parse as standalone when they're followed by Junk.
// Consequently, we only attach Comments once we know that the Message
// or the Term parsed successfully.
if (entry is Ast.Comment comment &&
blankLines == 0 && ps.Current != Eof)
{
// Stash the comment and decide what to do with it in the next pass.
lastComment = comment;
continue;
}
if (lastComment != null)
{
if (entry is Ast.MessageTermBase mt)
{
mt.Comment = lastComment;
if (_withSpans)
{
mt.Span.Start = lastComment.Span.Start;
}
}
else
{
entries.Add(lastComment);
}
// In either case, the stashed comment has been dealt with; clear it.
lastComment = null;
}
// No special logic for other types of entries.
entries.Add(entry);
}
var res = new Ast.Resource(entries);
if (_withSpans)
{
res.AddSpan(Position.Start, ps.GetPosition());
}
return(res);
}
Ast.Placeable _GetPlaceable(FtlParserStream ps)
{
ps.ExpectChar('{');
var expression = GetExpression(ps);
ps.ExpectChar('}');
return(new Ast.Placeable(expression));
}
public Ast.BaseComment _GetComment(FtlParserStream ps)
{
// 0 - comment
// 1 - group comment
// 2 - resource comment
int level = -1;
var content = new StringBuilder();
while (true)
{
int i = -1;
while (ps.CurrentIs('#') && (i < (level == -1 ? 2 : level)))
{
ps.Next();
i++;
}
if (level == -1)
{
level = i;
}
if (!ps.IsPeekNewLine())
{
ps.ExpectChar(' ');
int ch;
while ((ch = ps.TakeChar(x => x != '\r' && x != '\n')) != Eof)
{
content.Append((char)ch);
}
}
if (ps.IsPeekNextLineComment(level))
{
content.Append('\n');
ps.SkipNewLine();
}
else
{
break;
}
}
var text = content.ToString();
switch (level)
{
case 0:
return(new Ast.Comment(text));
case 1:
return(new Ast.GroupComment(text));
case 2:
return(new Ast.ResourceComment(text));
}
throw new InvalidOperationException($"Unknown level value '{level}'");
}
public static string TrimRight(string s)
{
int end = s.Length;
for (; end > 0 && FtlParserStream.IsWhite(s[end - 1]); --end)
{
}
return(s.Length == end ? s : s.Substring(0, end));
}
Ast.SyntaxNode _GetVariantList(FtlParserStream ps)
{
ps.ExpectChar('{');
ps.SkipInlineWs();
var variants = GetVariants(ps);
ps.ExpectIndent();
ps.ExpectChar('}');
return(new Ast.VariantList(variants));
}
Ast.Expression GetArgVal(FtlParserStream ps)
{
if (ps.IsNumberStart())
{
return(GetNumber(ps));
}
else if (ps.CurrentIs('"'))
{
return(GetString(ps));
}
throw new ParseException("E0012");
}
Ast.SyntaxNode _GetValue(FtlParserStream ps)
{
if (ps.CurrentIs('{'))
{
ps.Peek();
ps.PeekInlineWs();
if (ps.IsPeekNextLineVariantStart())
{
return(GetVariantList(ps));
}
}
return(GetPattern(ps));
}
CallArgs GetCallArgs(FtlParserStream ps)
{
var result = new CallArgs();
var argumentNames = new HashSet <string>();
ps.SkipInlineWs();
ps.SkipIndent();
while (true)
{
if (ps.Current == ')')
{
break;
}
var arg = GetCallArg(ps);
if (arg is Ast.NamedArgument narg)
{
if (argumentNames.Contains(narg.Name.Name))
{
throw new ParseException("E0022");
}
result.Named.Add(narg);
argumentNames.Add(narg.Name.Name);
}
else if (argumentNames.Count > 0)
{
throw new ParseException("E0021");
}
else
{
result.Positional.Add(arg);
}
ps.SkipInlineWs();
ps.SkipIndent();
if (ps.Current == ',')
{
ps.Next();
ps.SkipInlineWs();
ps.SkipIndent();
continue;
}
else
{
break;
}
}
return(result);
}
Ast.Identifier _GetIdentifier(FtlParserStream ps)
{
var name = new StringBuilder();
name.Append((char)ps.TakeIDStart());
int ch;
while ((ch = ps.TakeIDChar()) != Eof)
{
name.Append((char)ch);
}
return(new Ast.Identifier(name.ToString()));
}
Ast.SyntaxNode GetVariantKey(FtlParserStream ps)
{
var ch = ps.Current;
if (ch == Eof)
{
throw new ParseException("E0013");
}
if ((ch >= '0' && ch <= '9') || ch == '-')
{
return(GetNumber(ps));
}
return(GetVariantName(ps));
}
IReadOnlyList <Ast.Attribute> GetAttributes(FtlParserStream ps)
{
var attrs = new List <Ast.Attribute>();
while (true)
{
ps.ExpectIndent();
var attr = GetAttribute(ps);
attrs.Add(attr);
if (!ps.IsPeekNextLineAttributeStart())
{
break;
}
}
return(attrs);
}
string GetDigits(FtlParserStream ps)
{
var num = new StringBuilder();
int ch;
while ((ch = ps.TakeDigit()) != Eof)
{
num.Append((char)ch);
}
if (num.Length == 0)
{
throw new ParseException("E0004", "0-9");
}
return(num.ToString());
}
Ast.Attribute _GetAttribute(FtlParserStream ps)
{
ps.ExpectChar('.');
var key = GetIdentifier(ps);
ps.SkipInlineWs();
ps.ExpectChar('=');
if (ps.IsPeekValueStart())
{
ps.SkipIndent();
var value = GetPattern(ps);
return(new Ast.Attribute(key, value));
}
throw new ParseException("E0012");
}
public Ast.Entry GetEntry(FtlParserStream ps)
{
if (ps.CurrentIs('#'))
{
return(GetComment(ps));
}
if (ps.CurrentIs('-'))
{
return(GetTerm(ps));
}
if (ps.IsIdentifierStart())
{
return(GetMessage(ps));
}
throw new ParseException("E0002");
}
/// <summary>
/// Parse the first Message or Term in `source`.
///
/// Skip all encountered comments and start parsing at the first Message or
/// Term start. Return Junk if the parsing is not successful.
///
/// Preceding comments are ignored unless they contain syntax errors
/// themselves, in which case Junk for the invalid comment is returned.
/// </summary>
public Ast.Entry ParseEntry(TextReader source)
{
var ps = new FtlParserStream(source);
ps.SkipBlankLines();
while (ps.CurrentIs('#'))
{
var skipped = GetEntryOrJunk(ps);
if (skipped is Ast.Junk)
{
// Don't skip Junk comments.
return(skipped);
}
ps.SkipBlankLines();
}
return(GetEntryOrJunk(ps));
}
Ast.TextElement _GetTextElement(FtlParserStream ps)
{
var buffer = new StringBuilder();
int ch;
while ((ch = ps.Current) != Eof)
{
if (ch == '{')
{
return(new Ast.TextElement(buffer.ToString()));
}
if (ch == '\r' || ch == '\n')
{
if (!ps.IsPeekNextLineValue())
{
return(new Ast.TextElement(buffer.ToString()));
}
ps.SkipNewLine();
ps.SkipInlineWs();
// Add the new line to the buffer
buffer.Append((char)ch);
continue;
}
if (ch == '\\')
{
ps.Next();
GetEscapeSequence(ps,
new int[] { '{', '\\' }, buffer);
continue;
}
buffer.Append((char)ps.Current);
ps.Next();
}
return(new Ast.TextElement(buffer.ToString()));
}
Ast.VariantName _GetVariantName(FtlParserStream ps)
{
var name = new StringBuilder();
name.Append((char)ps.TakeIDStart());
while (true)
{
var ch = ps.TakeVariantNameChar();
if (ch != Eof)
{
name.Append((char)ch);
}
else
{
break;
}
}
return(new Ast.VariantName(TrimRight(name.ToString())));
}
Ast.NumberLiteral _GetNumber(FtlParserStream ps)
{
var num = new StringBuilder();
if (ps.CurrentIs('-'))
{
num.Append('-');
ps.Next();
}
num.Append(GetDigits(ps));
if (ps.CurrentIs('.'))
{
num.Append('.');
ps.Next();
num.Append(GetDigits(ps));
}
return(new Ast.NumberLiteral(num.ToString()));
}
Ast.Expression _GetLiteral(FtlParserStream ps)
{
var ch = ps.Current;
if (ch == Eof)
{
throw new ParseException("E0014");
}
if (ch == '$')
{
ps.Next();
var id = GetIdentifier(ps);
return(new Ast.VariableReference(id));
}
if (ps.IsIdentifierStart())
{
var name = GetIdentifier(ps);
return(new Ast.MessageReference(name));
}
if (ps.IsNumberStart())
{
return(GetNumber(ps));
}
if (ch == '-')
{
var id = GetTermIdentifier(ps);
return(new Ast.TermReference(id));
}
if (ch == '"')
{
return(GetString(ps));
}
throw new ParseException("E0014");
}
T SpanWrapper <T>(FtlParserStream ps, Func <T> wrappedFn) where T : Ast.SyntaxNode
{
if (!_withSpans)
{
return(wrappedFn());
}
var start = ps.GetPosition();
var node = wrappedFn();
// Don't re-add the span if the node already has it. This may happen when
// one decorated function calls another decorated function.
if (node.Span != null)
{
return(node);
}
var end = ps.GetPosition();
node.AddSpan(start, end);
return(node);
}
Ast.Pattern _GetPattern(FtlParserStream ps)
{
var elements = new List <Ast.SyntaxNode>();
ps.SkipInlineWs();
int ch;
while ((ch = ps.Current) != Eof)
{
// The end condition for GetPattern's while loop is a newline
// which is not followed by a valid pattern continuation.
if (ps.IsPeekNewLine() && !ps.IsPeekNextLineValue())
{
break;
}
if (ch == '{')
{
var element = GetPlaceable(ps);
elements.Add(element);
}
else
{
var element = GetTextElement(ps);
elements.Add(element);
}
}
// Trim trailing whitespace.
if (elements.Count > 0 &&
elements[elements.Count - 1] is Ast.TextElement te)
{
te.Value = TrimRight(te.Value);
}
return(new Ast.Pattern(elements));
}
void GetEscapeSequence(FtlParserStream ps, int[] specials,
StringBuilder buffer)
{
int next = ps.Current;
if (Array.IndexOf(specials, next) >= 0)
{
ps.Next();
buffer.Append('\\').Append((char)next);
return;
}
if (next == 'u')
{
ps.Next();
char[] sequence = new char[4];
for (int i = 0; i < 4; ++i)
{
int ch = ps.TakeHexDigit();
if (ch == Eof)
{
var msg = new String(sequence, 0, i);
if (ps.Current != Eof)
{
msg += (char)ps.Current;
}
throw new ParseException("E0026", msg);
}
sequence[i] = (char)ch;
}
buffer.Append("\\u").Append(sequence);
return;
}
throw new ParseException("E0025",
next == Eof ? "" : ((char)next).ToString());
}
