Original message:
SIL Parsing: add plumbing to know when we're parsing a .sil file
Enhance the lexer to lex "sil" as a keyword in sil mode.
Swift SVN r4988
Create a new FallthroughStmt, which transfers control from a 'case' or 'default' block to the next 'case' or 'default' block within a switch. Implement parsing and sema for FallthroughStmt, which syntactically consists of a single 'fallthrough' keyword. Sema verifies that 'fallthrough' actually appears inside a switch statement and that there is a following case or default block to pass control to.
SILGen/IRGen support forthcoming.
Swift SVN r4653
Now that we enforce semicolon or newline separation between statements, we can relax the whitespace requirements on '(' and '[' tokens. A "following" token is now just a token that isn't at the start of a line, and any token can be a "starting" token. This allows for:
a(b)
a (b)
a[b]
a [b]
to parse as applications and subscripts, and:
a
(b)
a
[b]
to parse as an expr followed by a tuple or an expr followed by a container literal.
Swift SVN r4573
Provide distinct syntax 'a as T' for coercions and 'a as! T' for unchecked downcasts, and add type-checker logic specialized to coercions and downcasts for these expressions. Change the AST representation of ExplicitCastExpr to keep the destination type as a TypeLoc rather than a subexpression, and change the names of the nodes to UncheckedDowncast and UncheckedSuperToArchetype to make their unchecked-ness explicit and disambiguate them from future checked casts.
In order to keep the changes staged, this doesn't yet affect the T(x) constructor syntax, which will for the time being still perform any construction, coercion, or cast.
Swift SVN r4498
Implement the syntax 'if x then y else z', which evaluates to 'y' if 'x' is true or 'z' if 'x' is false. 'x' must be a valid logic value, and 'y' and 'z' must be implicitly convertible to a common type.
Swift SVN r4407
Implement switch statements with simple value comparison to get the drudge work of parsing and generating switches in place. Cases are checked using a '=~' operator to compare the subject of the switch to the value in the case. Unlike a C switch, cases each have their own scope and don't fall through. 'break' and 'continue' apply to an outer loop rather to the switch itself. Multiple case values can be specified in a comma-separated list, as in 'case 1, 2, 3, 4:'. Currently no effort is made to check for duplicate cases or to rank cases by match strength; cases are just checked in source order, and the first one wins (aside from 'default', which is branched to if all cases fail).
Swift SVN r4359
When parsing an expression, if we see the production [[identifier '<']], use the following heuristic to choose whether to parse it as a type list or as an operator expression:
- Speculatively parse the subsequent production as a type parameter list.
- If the parse succeeds, examine the token after the closing '>'. If it is one of the following:
l_paren_following
l_square_following
r_paren
r_square
l_brace
r_brace
comma
semicolon
period
then accept the parse as a type list.
- If the parse fails, or if the type list is not followed by one of those tokens, reject the type list and parse as an operator expression.
This only implements the parsing rule. The type parameters are just dropped on the floor--the AST representation and Sema changes are forthcoming. Encouragingly, no test or library code appears to be broken by this rule.
Swift SVN r4044
APFloat's parser gives us the parsing for free. Unlike C99 we require at least one digit on both sides of the hexadecimal point in order to allow '0x1.method()' expressions, similar to Dave's proposed change to float lexing. Also, we were requiring a sign after 'e' in the exponent, which is inconsistent with C, C++, and the Java regex we claim to follow, so I made the exponent sign optional.
Swift SVN r3940
If we generalize John's insight about l_(paren|square) being about
"starting" and "following" tokens, then we can detect many statement
or declaration boundaries that are lacking either white space or a
semicolon.
Ensuring some amount of whitespace between statements and declarations
is good for future proofing.
Swift SVN r3914
In Swift the "in" keyword is really a form of punctuation, and highly
context specific punctuation at that. It never begins a statement, nor
does the grammar require it be statement keyword. The grammar also
doesn't use it outside of for-each loops, and its use within a for-each
loop is highly unambiguous.
Thanks to Chris for the performance related feedback. This improves the
performance of getter/setter parsing as well.
Swift SVN r3880
Dave noted that he's trying to scrub the parser codebase of wishy-washy 'isAnyLParen' and 'isAnyLBrace' calls by consistently lexing opening bracket tokens correctly to begin with. Since currently only 'super' and 'constructor' need to be lexed like identifiers for expression syntax (and, in the future, 'this' and 'This' when those become keywords), mark them as a special kind of 'identifier keyword' in Tokens.def and roll back some of the changes I made to make parsing other decls support either token.
Swift SVN r3848
Opening brackets after a keyword have to lex as l_paren_call or l_square_subscript in order for expressions like 'super.constructor()' or 'super[i]' to parse. While we're here, let's move the keyword and punctuator list to a metaprogrammable Tokens.def header too. Update decl and stmt parsers to use 'isAnyLParen' so that, e.g., 'constructor(' and 'constructor (' both work as before.
Swift SVN r3846
The lexer now models tuples, patterns, subscripting, function calls, and
field access robustly. The output tokens are now better named as well:
l_paren and l_paren_call, and l_square and l_square_subscript. It
should be much more clear now which one to use. Also, the use of
l_paren or l_square will not arbitrarily flip flop if the token before
it is a keyword or if the token before it was the trailing ']' of an
attribute list. Similarly, tuples will always cause the lexer to produce
l_paren, regardless if the user typed '((x,y))' or '( (x,y))'.
When we someday add array literals, the right token is now naturally
falling out of the lexer.
Swift SVN r3840
resulting token goes back through the lexer to get the appropriate
token kind. Thanks to Chris for spotting this.
Also, document the '<' and '>' splitting behavior in LangRef.
Swift SVN r2192
and use this information as cues in the language. Right now,
we do not accept things like "-- *i" because the prefix
operator is not correctly right-bound; instead you have to
write "--(*i)". I'm okay with that; I did add a specialized
diagnostic recognizing operator-binary in a place where we're
expecting a potential operator-prefix.
Swift SVN r2161
e.g. "foo is \(i+j)". This implements rdar://11223686
Doug implemented all the hard parts of this. I ripped out support for nested string
literals (i.e. string literals within an interpolated string), which simplified the
approach and defined away some problems with his patch in progress. I plan a few refinements
on top of this basic patch.
Swift SVN r1738
Per discussion, this should probably be "no newline since the last
token", but that decision should be made simultaneously for ( and [.
Swift SVN r1461
