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501 lines
16 KiB
C++
501 lines
16 KiB
C++
//===--- ParsePattern.cpp - Swift Language Parser for Patterns ------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Pattern Parsing and AST Building
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//
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//===----------------------------------------------------------------------===//
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#include "swift/Parse/Parser.h"
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#include "swift/AST/ExprHandle.h"
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#include "llvm/ADT/StringMap.h"
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using namespace swift;
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/// Parse function arguments.
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/// func-arguments:
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/// curried-arguments | selector-arguments
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/// curried-arguments:
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/// pattern-tuple+
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/// selector-arguments:
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/// '(' selector-element ')' (identifier '(' selector-element ')')+
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/// selector-element:
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/// identifier '(' pattern-atom (':' type-annotation)? ('=' expr)? ')'
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static bool parseCurriedFunctionArguments(Parser &P,
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SmallVectorImpl<Pattern*> &argPat,
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SmallVectorImpl<Pattern*> &bodyPat) {
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// parseFunctionArguments parsed the first argument pattern.
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// Parse additional curried argument clauses as long as we can.
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while (P.Tok.is(tok::l_paren)) {
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ParserResult<Pattern> pattern = P.parsePatternTuple(/*AllowInitExpr=*/false);
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if (pattern.isNull())
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return true;
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else {
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argPat.push_back(pattern.get());
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bodyPat.push_back(pattern.get());
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}
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}
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return false;
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}
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/// \brief Determine the kind of a default argument given a parsed
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/// expression that has not yet been type-checked.
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static DefaultArgumentKind getDefaultArgKind(ExprHandle *init) {
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if (!init || !init->getExpr())
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return DefaultArgumentKind::None;
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auto magic = dyn_cast<MagicIdentifierLiteralExpr>(init->getExpr());
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if (!magic)
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return DefaultArgumentKind::Normal;
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switch (magic->getKind()) {
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case MagicIdentifierLiteralExpr::Column:
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return DefaultArgumentKind::Column;
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case MagicIdentifierLiteralExpr::File:
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return DefaultArgumentKind::File;
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case MagicIdentifierLiteralExpr::Line:
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return DefaultArgumentKind::Line;
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}
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}
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static bool parseSelectorArgument(Parser &P,
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SmallVectorImpl<TuplePatternElt> &argElts,
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SmallVectorImpl<TuplePatternElt> &bodyElts,
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llvm::StringMap<VarDecl*> &selectorNames,
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SourceLoc &rp)
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{
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ParserResult<Pattern> argPattern = P.parsePatternIdentifier();
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assert(argPattern.isNonNull() &&
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"selector argument did not start with an identifier!");
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// Check that a selector name isn't used multiple times, which would
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// lead to the function type having multiple arguments with the same name.
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if (NamedPattern *name = dyn_cast<NamedPattern>(argPattern.get())) {
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VarDecl *decl = name->getDecl();
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StringRef id = decl->getName().str();
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auto prevName = selectorNames.find(id);
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if (prevName != selectorNames.end()) {
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P.diagnoseRedefinition(prevName->getValue(), decl);
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} else {
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selectorNames[id] = decl;
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}
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}
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if (!P.Tok.is(tok::l_paren)) {
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P.diagnose(P.Tok.getLoc(),
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diag::func_selector_without_paren);
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return true;
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}
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P.consumeToken();
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if (P.Tok.is(tok::r_paren)) {
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P.diagnose(P.Tok, diag::func_selector_with_not_one_argument);
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return true;
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}
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ParserResult<Pattern> bodyPattern = P.parsePatternAtom();
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if (bodyPattern.isNull()) {
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P.skipUntil(tok::r_paren);
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return true;
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}
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if (P.consumeIf(tok::colon)) {
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TypeRepr *type = P.parseTypeAnnotation();
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if (!type) {
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P.skipUntil(tok::r_paren);
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return true;
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}
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argPattern = makeParserResult(
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new (P.Context) TypedPattern(argPattern.get(), type));
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bodyPattern = makeParserResult(
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new (P.Context) TypedPattern(bodyPattern.get(), type));
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}
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ExprHandle *init = nullptr;
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if (P.consumeIf(tok::equal)) {
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NullablePtr<Expr> initR =
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P.parseExpr(diag::expected_initializer_expr);
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if (initR.isNull()) {
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P.skipUntil(tok::r_paren);
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return true;
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}
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init = ExprHandle::get(P.Context, initR.get());
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}
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if (P.Tok.is(tok::comma)) {
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P.diagnose(P.Tok, diag::func_selector_with_not_one_argument);
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P.skipUntil(tok::r_paren);
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return true;
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}
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if (P.Tok.isNot(tok::r_paren)) {
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P.diagnose(P.Tok, diag::expected_rparen_tuple_pattern_list);
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return true;
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}
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rp = P.consumeToken(tok::r_paren);
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argElts.push_back(TuplePatternElt(argPattern.get(), init,
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getDefaultArgKind(init)));
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bodyElts.push_back(TuplePatternElt(bodyPattern.get(), init,
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getDefaultArgKind(init)));
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return false;
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}
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static Pattern *getFirstSelectorPattern(ASTContext &Context,
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const Pattern *argPattern,
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SourceLoc loc)
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{
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Pattern *pattern = new (Context) AnyPattern(loc);
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if (auto typed = dyn_cast<TypedPattern>(argPattern)) {
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pattern = new (Context) TypedPattern(pattern, typed->getTypeLoc());
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}
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return pattern;
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}
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static bool parseSelectorFunctionArguments(Parser &P,
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SmallVectorImpl<Pattern*> &argPat,
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SmallVectorImpl<Pattern*> &bodyPat,
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Pattern *firstPattern)
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{
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SourceLoc lp;
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SmallVector<TuplePatternElt, 8> argElts;
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SmallVector<TuplePatternElt, 8> bodyElts;
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// For the argument pattern, try to convert the first parameter pattern to
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// an anonymous AnyPattern of the same type as the body parameter.
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if (ParenPattern *firstParen = dyn_cast<ParenPattern>(firstPattern)) {
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bodyElts.push_back(TuplePatternElt(firstParen->getSubPattern()));
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lp = firstParen->getLParenLoc();
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argElts.push_back(TuplePatternElt(
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getFirstSelectorPattern(P.Context,
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firstParen->getSubPattern(),
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firstParen->getLoc())));
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} else if (TuplePattern *firstTuple = dyn_cast<TuplePattern>(firstPattern)) {
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if (firstTuple->getNumFields() != 1) {
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P.diagnose(P.Tok, diag::func_selector_with_not_one_argument);
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return true;
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}
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TuplePatternElt const &firstElt = firstTuple->getFields()[0];
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bodyElts.push_back(firstElt);
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lp = firstTuple->getLParenLoc();
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argElts.push_back(TuplePatternElt(
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getFirstSelectorPattern(P.Context,
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firstElt.getPattern(),
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firstTuple->getLoc()),
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firstElt.getInit(),
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firstElt.getDefaultArgKind()));
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} else
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llvm_unreachable("unexpected function argument pattern!");
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// Parse additional selectors as long as we can.
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SourceLoc rp;
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llvm::StringMap<VarDecl*> selectorNames;
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for (;;) {
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if (P.isStartOfBindingName(P.Tok)) {
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if (parseSelectorArgument(P, argElts, bodyElts, selectorNames, rp)) {
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return true;
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}
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} else if (P.Tok.is(tok::l_paren)) {
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P.diagnose(P.Tok, diag::func_selector_with_curry);
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return true;
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} else
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break;
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}
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argPat.push_back(TuplePattern::create(P.Context, lp, argElts, rp));
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bodyPat.push_back(TuplePattern::create(P.Context, lp, bodyElts, rp));
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return false;
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}
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bool Parser::parseFunctionArguments(SmallVectorImpl<Pattern*> &argPatterns,
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SmallVectorImpl<Pattern*> &bodyPatterns) {
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// Parse the first function argument clause.
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ParserResult<Pattern> pattern = parsePatternTuple(/*AllowInitExpr=*/true);
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if (pattern.isNull())
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return true;
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else {
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Pattern *firstPattern = pattern.get();
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if (isStartOfBindingName(Tok)) {
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// This looks like a selector-style argument. Try to convert the first
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// argument pattern into a single argument type and parse subsequent
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// selector forms.
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return parseSelectorFunctionArguments(*this,
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argPatterns, bodyPatterns,
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pattern.get());
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} else {
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argPatterns.push_back(firstPattern);
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bodyPatterns.push_back(firstPattern);
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return parseCurriedFunctionArguments(*this,
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argPatterns, bodyPatterns);
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}
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}
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}
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/// parseFunctionSignature - Parse a function definition signature.
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/// func-signature:
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/// func-arguments func-signature-result?
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/// func-signature-result:
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/// '->' type
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///
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/// Note that this leaves retType as null if unspecified.
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bool Parser::parseFunctionSignature(SmallVectorImpl<Pattern*> &argPatterns,
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SmallVectorImpl<Pattern*> &bodyPatterns,
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TypeRepr *&retType) {
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bool HadParseError = parseFunctionArguments(argPatterns, bodyPatterns);
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// If there's a trailing arrow, parse the rest as the result type.
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if (consumeIf(tok::arrow)) {
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if (!(retType = parseType()))
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return true;
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} else {
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// Otherwise, we leave retType null.
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retType = nullptr;
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}
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return HadParseError;
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}
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/// Parse a pattern.
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/// pattern ::= pattern-atom
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/// pattern ::= pattern-atom ':' type-annotation
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ParserResult<Pattern> Parser::parsePattern() {
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// First, parse the pattern atom.
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ParserResult<Pattern> pattern = parsePatternAtom();
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if (pattern.isNull())
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return nullptr;
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// Now parse an optional type annotation.
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if (consumeIf(tok::colon)) {
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TypeRepr *type = parseTypeAnnotation();
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if (!type)
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return nullptr;
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pattern = makeParserResult(new (Context) TypedPattern(pattern.get(), type));
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}
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return pattern;
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}
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/// \brief Determine whether this token can start a pattern.
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bool Parser::isStartOfPattern(Token tok) {
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return tok.is(tok::kw__) || tok.is(tok::identifier) || tok.is(tok::l_paren);
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}
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/// \brief Determine whether this token can start a binding name, whether an
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/// identifier or the special discard-value binding '_'.
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bool Parser::isStartOfBindingName(Token tok) {
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return tok.is(tok::kw__) || tok.is(tok::identifier);
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}
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Pattern *Parser::createBindingFromPattern(SourceLoc loc,
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Identifier name) {
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VarDecl *var = new (Context) VarDecl(loc, name, Type(), nullptr);
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return new (Context) NamedPattern(var);
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}
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/// Parse an identifier as a pattern.
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ParserResult<Pattern> Parser::parsePatternIdentifier() {
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SourceLoc loc = Tok.getLoc();
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if (consumeIf(tok::kw__)) {
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return makeParserResult(new (Context) AnyPattern(loc));
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}
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StringRef text = Tok.getText();
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if (consumeIf(tok::identifier)) {
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Identifier ident = Context.getIdentifier(text);
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return makeParserResult(createBindingFromPattern(loc, ident));
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}
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return nullptr;
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}
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/// Parse a pattern "atom", meaning the part that precedes the
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/// optional type annotation.
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///
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/// pattern-atom ::= identifier
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/// pattern-atom ::= '_'
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/// pattern-atom ::= pattern-tuple
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ParserResult<Pattern> Parser::parsePatternAtom() {
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switch (Tok.getKind()) {
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case tok::l_paren:
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return parsePatternTuple(/*AllowInitExpr*/false);
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case tok::identifier:
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case tok::kw__:
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return parsePatternIdentifier();
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#define IDENTIFIER_KEYWORD(kw) case tok::kw_##kw:
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#include "swift/Parse/Tokens.def"
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diagnose(Tok, diag::expected_pattern_is_keyword);
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consumeToken();
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return nullptr;
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default:
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diagnose(Tok, diag::expected_pattern);
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return nullptr;
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}
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}
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Optional<TuplePatternElt> Parser::parsePatternTupleElement(bool allowInitExpr) {
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// Parse the pattern.
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ParserResult<Pattern> pattern = parsePattern();
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if (pattern.isNull())
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return Nothing;
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// Parse the optional initializer.
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ExprHandle *init = nullptr;
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if (Tok.is(tok::equal)) {
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SourceLoc EqualLoc = consumeToken();
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NullablePtr<Expr> initR = parseExpr(diag::expected_initializer_expr);
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if (!allowInitExpr) {
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auto inFlight = diagnose(EqualLoc, diag::non_func_decl_pattern_init);
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if (initR.isNonNull())
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inFlight.fixItRemove(SourceRange(EqualLoc, initR.get()->getEndLoc()));
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}
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// FIXME: Silently dropping initializer expressions where they aren't
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// permitted.
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if (allowInitExpr && initR.isNonNull())
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init = ExprHandle::get(Context, initR.get());
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}
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return TuplePatternElt(pattern.get(), init, getDefaultArgKind(init));
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}
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/// Parse a tuple pattern.
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///
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/// pattern-tuple:
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/// '(' pattern-tuple-body? ')'
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/// pattern-tuple-body:
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/// pattern-tuple-element (',' pattern-tuple-body)*
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ParserResult<Pattern> Parser::parsePatternTuple(bool AllowInitExpr) {
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SourceLoc RPLoc, LPLoc = consumeToken(tok::l_paren);
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SourceLoc EllipsisLoc;
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// Parse all the elements.
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SmallVector<TuplePatternElt, 8> elts;
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bool Invalid = parseList(tok::r_paren, LPLoc, RPLoc,
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tok::comma, /*OptionalSep=*/false,
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diag::expected_rparen_tuple_pattern_list,
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[&] () -> bool {
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// Parse the pattern tuple element.
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Optional<TuplePatternElt> elt = parsePatternTupleElement(AllowInitExpr);
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if (!elt)
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return true;
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// Add this element to the list.
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elts.push_back(*elt);
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// If there is no ellipsis, we're done with the element.
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if (Tok.isNot(tok::ellipsis))
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return false;
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SourceLoc ellLoc = consumeToken(tok::ellipsis);
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// An element cannot have both an initializer and an ellipsis.
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if (elt->getInit()) {
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diagnose(ellLoc, diag::tuple_ellipsis_init)
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.highlight(elt->getInit()->getExpr()->getSourceRange());
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return false;
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}
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// An ellipsis element shall have a specified element type.
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// FIXME: This seems unnecessary.
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TypedPattern *typedPattern = dyn_cast<TypedPattern>(elt->getPattern());
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if (!typedPattern) {
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diagnose(ellLoc, diag::untyped_pattern_ellipsis)
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.highlight(elt->getPattern()->getSourceRange());
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return false;
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}
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// Variadic elements must come last.
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// FIXME: Unnecessary restriction. It makes conversion more interesting,
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// but is not complicated to support.
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if (Tok.is(tok::r_paren)) {
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EllipsisLoc = ellLoc;
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} else {
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diagnose(ellLoc, diag::ellipsis_pattern_not_at_end);
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}
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return false;
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});
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if (Invalid)
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return nullptr;
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return makeParserResult(TuplePattern::createSimple(
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Context, LPLoc, elts, RPLoc, EllipsisLoc.isValid(), EllipsisLoc));
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}
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ParserResult<Pattern> Parser::parseMatchingPattern() {
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// TODO: Since we expect a pattern in this position, we should optimistically
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// parse pattern nodes for productions shared by pattern and expression
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// grammar. For short-term ease of initial implementation, we always go
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// through the expr parser for ambiguious productions.
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// Parse productions that can only be patterns.
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// matching-pattern ::= matching-pattern-var
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if (Tok.is(tok::kw_var)) {
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return parseMatchingPatternVar();
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}
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// matching-pattern ::= '_'
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if (Tok.is(tok::kw__)) {
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return makeParserResult(new (Context) AnyPattern(consumeToken()));
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}
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// matching-pattern ::= 'is' type
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if (Tok.is(tok::kw_is)) {
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return parseMatchingPatternIsa();
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}
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// matching-pattern ::= expr
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// Fall back to expression parsing for ambiguous forms. Name lookup will
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// disambiguate.
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NullablePtr<Expr> subExpr = parseExpr(diag::expected_pattern);
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if (subExpr.isNull())
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return nullptr;
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return makeParserResult(new (Context) ExprPattern(subExpr.get()));
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}
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ParserResult<Pattern> Parser::parseMatchingPatternVar() {
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// 'var' patterns shouldn't nest.
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if (VarPatternDepth >= 1)
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diagnose(Tok.getLoc(), diag::var_pattern_in_var);
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VarPatternScope scope(*this);
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SourceLoc varLoc = consumeToken(tok::kw_var);
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ParserResult<Pattern> subPattern = parseMatchingPattern();
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if (subPattern.isNull())
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return nullptr;
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return makeParserResult(new (Context) VarPattern(varLoc, subPattern.get()));
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}
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ParserResult<Pattern> Parser::parseMatchingPatternIsa() {
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SourceLoc isLoc = consumeToken(tok::kw_is);
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TypeRepr *castType = parseType();
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if (!castType)
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return nullptr;
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return makeParserResult(new (Context) IsaPattern(isLoc, castType));
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}
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bool Parser::isOnlyStartOfMatchingPattern() {
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return Tok.is(tok::kw_var)
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|| Tok.is(tok::kw__)
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|| Tok.is(tok::kw_is);
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}
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