Patterns parsing: add support for guards.

Bug: #50035 Change-Id: I21db09c9d8c1d359e1b125eea2bae2749cdb72fd Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/264101 Reviewed-by: Jens Johansen <[email protected]> Reviewed-by: Konstantin Shcheglov <[email protected]> Commit-Queue: Paul Berry <[email protected]>
dart-lang · Oct 14, 2022 · 9aab3c7 · 9aab3c7
1 parent 4cf63fb
commit 9aab3c7
Show file tree

Hide file tree

Showing 48 changed files with 1,649 additions and 9 deletions.
diff --git a/pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart b/pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart
@@ -6240,8 +6240,14 @@ class Parser {
     if (allowPatterns && optional('case', next)) {
       Token case_ = token = next;
       token = parsePattern(token);
+      next = token.next!;
+      Token? when;
+      if (optional('when', next)) {
+        when = token = next;
+        token = parseExpression(token);
+      }
       token = ensureCloseParen(token, begin);
-      listener.handleParenthesizedCondition(begin, case_, null);
+      listener.handleParenthesizedCondition(begin, case_, when);
     } else {
       token = ensureCloseParen(token, begin);
       listener.handleParenthesizedCondition(
@@ -8258,9 +8264,15 @@ class Parser {
           } else {
             token = parseExpression(caseKeyword);
           }
+          Token? next = token.next!;
+          Token? when;
+          if (optional('when', next)) {
+            when = token = next;
+            token = parseExpression(token);
+          }
           token = ensureColon(token);
-          listener.endCaseExpression(null, token);
-          listener.handleCaseMatch(caseKeyword, null, token);
+          listener.endCaseExpression(when, token);
+          listener.handleCaseMatch(caseKeyword, when, token);
           expressionCount++;
           peek = peekPastLabels(token.next!);
         } else if (expressionCount > 0) {

diff --git a/pkg/_fe_analyzer_shared/lib/src/scanner/token.dart b/pkg/_fe_analyzer_shared/lib/src/scanner/token.dart
@@ -327,14 +327,17 @@ class Keyword extends TokenType {
   static const Keyword VOID =
       const Keyword(/* index = */ 145, "void", "VOID", KeywordStyle.reserved);
 
+  static const Keyword WHEN =
+      const Keyword(/* index = */ 146, "when", 'WHEN', KeywordStyle.pseudo);
+
   static const Keyword WHILE =
-      const Keyword(/* index = */ 146, "while", "WHILE", KeywordStyle.reserved);
+      const Keyword(/* index = */ 147, "while", "WHILE", KeywordStyle.reserved);
 
   static const Keyword WITH =
-      const Keyword(/* index = */ 147, "with", "WITH", KeywordStyle.reserved);
+      const Keyword(/* index = */ 148, "with", "WITH", KeywordStyle.reserved);
 
   static const Keyword YIELD =
-      const Keyword(/* index = */ 148, "yield", "YIELD", KeywordStyle.pseudo);
+      const Keyword(/* index = */ 149, "yield", "YIELD", KeywordStyle.pseudo);
 
   static const List<Keyword> values = const <Keyword>[
     ABSTRACT,
@@ -404,6 +407,7 @@ class Keyword extends TokenType {
     TYPEDEF,
     VAR,
     VOID,
+    WHEN,
     WHILE,
     WITH,
     YIELD,
@@ -1978,6 +1982,7 @@ const List<TokenType> _tokenTypesByIndex = [
   Keyword.TYPEDEF,
   Keyword.VAR,
   Keyword.VOID,
+  Keyword.WHEN,
   Keyword.WHILE,
   Keyword.WITH,
   Keyword.YIELD,

diff --git a/pkg/analyzer/lib/src/dart/ast/ast.dart b/pkg/analyzer/lib/src/dart/ast/ast.dart
@@ -1483,6 +1483,7 @@ class CaseClauseImpl extends AstNodeImpl implements CaseClause {
     required this.whenClause,
   }) {
     _becomeParentOf(pattern);
+    _becomeParentOf(whenClause);
   }
 
   @override

diff --git a/pkg/analyzer/lib/src/fasta/ast_builder.dart b/pkg/analyzer/lib/src/fasta/ast_builder.dart
@@ -3282,12 +3282,17 @@ class AstBuilder extends StackListener {
     debugEvent("CaseMatch");
 
     if (_featureSet.isEnabled(Feature.patterns)) {
+      WhenClauseImpl? whenClause;
+      if (when != null) {
+        var expression = pop() as ExpressionImpl;
+        whenClause = WhenClauseImpl(whenKeyword: when, expression: expression);
+      }
       var pattern = pop() as DartPatternImpl;
       push(SwitchPatternCaseImpl(
           labels: <Label>[],
           keyword: caseKeyword,
           pattern: pattern,
-          whenClause: null,
+          whenClause: whenClause,
           colon: colon,
           statements: <Statement>[]));
     } else {
@@ -4561,10 +4566,14 @@ class AstBuilder extends StackListener {
     ExpressionImpl condition;
     CaseClauseImpl? caseClause;
     if (case_ != null) {
-      // TODO(paulberry): what about a guard?
+      WhenClauseImpl? whenClause;
+      if (when != null) {
+        var expression = pop() as ExpressionImpl;
+        whenClause = WhenClauseImpl(whenKeyword: when, expression: expression);
+      }
       var pattern = pop() as DartPatternImpl;
       caseClause = CaseClauseImpl(
-          caseKeyword: case_, pattern: pattern, whenClause: null);
+          caseKeyword: case_, pattern: pattern, whenClause: whenClause);
     }
     condition = pop() as ExpressionImpl;
     push(_ParenthesizedCondition(leftParenthesis, condition, caseClause));

diff --git a/pkg/analyzer/test/generated/patterns_parser_test.dart b/pkg/analyzer/test/generated/patterns_parser_test.dart
@@ -21,6 +21,238 @@ main() {
 class PatternsTest extends ParserDiagnosticsTest {
   late FindNode findNode;
 
+  test_caseHead_withClassicPattern_guarded_insideIfStatement() {
+    _parse('''
+void f(x) {
+  if (x case 0 when true) {}
+}
+''');
+    var node = findNode.ifStatement('case');
+    assertParsedNodeText(node, r'''
+IfStatement
+  ifKeyword: if
+  leftParenthesis: (
+  condition: SimpleIdentifier
+    token: x
+  caseClause: CaseClause
+    caseKeyword: case
+    pattern: ConstantPattern
+      expression: IntegerLiteral
+        literal: 0
+    whenClause: WhenClause
+      whenKeyword: when
+      expression: BooleanLiteral
+        literal: true
+  rightParenthesis: )
+  thenStatement: Block
+    leftBracket: {
+    rightBracket: }
+''');
+  }
+
+  test_caseHead_withClassicPattern_guarded_insideSwitchStatement() {
+    _parse('''
+void f(x) {
+  switch (x) {
+    case 0 when true:
+      break;
+  }
+}
+''');
+    var node = findNode.switchPatternCase('case');
+    assertParsedNodeText(node, r'''
+SwitchPatternCase
+  keyword: case
+  pattern: ConstantPattern
+    expression: IntegerLiteral
+      literal: 0
+  whenClause: WhenClause
+    whenKeyword: when
+    expression: BooleanLiteral
+      literal: true
+  colon: :
+  statements
+    BreakStatement
+      breakKeyword: break
+      semicolon: ;
+''');
+  }
+
+  test_caseHead_withClassicPattern_unguarded_insideIfStatement() {
+    _parse('''
+void f(x) {
+  if (x case 0) {}
+}
+''');
+    var node = findNode.ifStatement('case');
+    assertParsedNodeText(node, r'''
+IfStatement
+  ifKeyword: if
+  leftParenthesis: (
+  condition: SimpleIdentifier
+    token: x
+  caseClause: CaseClause
+    caseKeyword: case
+    pattern: ConstantPattern
+      expression: IntegerLiteral
+        literal: 0
+  rightParenthesis: )
+  thenStatement: Block
+    leftBracket: {
+    rightBracket: }
+''');
+  }
+
+  test_caseHead_withClassicPattern_unguarded_insideSwitchStatement() {
+    _parse('''
+void f(x) {
+  switch (x) {
+    case 0:
+      break;
+  }
+}
+''');
+    var node = findNode.switchPatternCase('case');
+    assertParsedNodeText(node, r'''
+SwitchPatternCase
+  keyword: case
+  pattern: ConstantPattern
+    expression: IntegerLiteral
+      literal: 0
+  colon: :
+  statements
+    BreakStatement
+      breakKeyword: break
+      semicolon: ;
+''');
+  }
+
+  test_caseHead_withNewPattern_guarded_insideIfStatement() {
+    _parse('''
+void f(x) {
+  if (x case 0 as int when true) {}
+}
+''');
+    var node = findNode.ifStatement('case');
+    assertParsedNodeText(node, r'''
+IfStatement
+  ifKeyword: if
+  leftParenthesis: (
+  condition: SimpleIdentifier
+    token: x
+  caseClause: CaseClause
+    caseKeyword: case
+    pattern: CastPattern
+      pattern: ConstantPattern
+        expression: IntegerLiteral
+          literal: 0
+      asToken: as
+      type: NamedType
+        name: SimpleIdentifier
+          token: int
+    whenClause: WhenClause
+      whenKeyword: when
+      expression: BooleanLiteral
+        literal: true
+  rightParenthesis: )
+  thenStatement: Block
+    leftBracket: {
+    rightBracket: }
+''');
+  }
+
+  test_caseHead_withNewPattern_guarded_insideSwitchStatement() {
+    _parse('''
+void f(x) {
+  switch (x) {
+    case 0 as int when true:
+      break;
+  }
+}
+''');
+    var node = findNode.switchPatternCase('case');
+    assertParsedNodeText(node, r'''
+SwitchPatternCase
+  keyword: case
+  pattern: CastPattern
+    pattern: ConstantPattern
+      expression: IntegerLiteral
+        literal: 0
+    asToken: as
+    type: NamedType
+      name: SimpleIdentifier
+        token: int
+  whenClause: WhenClause
+    whenKeyword: when
+    expression: BooleanLiteral
+      literal: true
+  colon: :
+  statements
+    BreakStatement
+      breakKeyword: break
+      semicolon: ;
+''');
+  }
+
+  test_caseHead_withNewPattern_unguarded_insideIfStatement() {
+    _parse('''
+void f(x) {
+  if (x case 0 as int) {}
+}
+''');
+    var node = findNode.ifStatement('case');
+    assertParsedNodeText(node, r'''
+IfStatement
+  ifKeyword: if
+  leftParenthesis: (
+  condition: SimpleIdentifier
+    token: x
+  caseClause: CaseClause
+    caseKeyword: case
+    pattern: CastPattern
+      pattern: ConstantPattern
+        expression: IntegerLiteral
+          literal: 0
+      asToken: as
+      type: NamedType
+        name: SimpleIdentifier
+          token: int
+  rightParenthesis: )
+  thenStatement: Block
+    leftBracket: {
+    rightBracket: }
+''');
+  }
+
+  test_caseHead_withNewPattern_unguarded_insideSwitchStatement() {
+    _parse('''
+void f(x) {
+  switch (x) {
+    case 0 as int:
+      break;
+  }
+}
+''');
+    var node = findNode.switchPatternCase('case');
+    assertParsedNodeText(node, r'''
+SwitchPatternCase
+  keyword: case
+  pattern: CastPattern
+    pattern: ConstantPattern
+      expression: IntegerLiteral
+        literal: 0
+    asToken: as
+    type: NamedType
+      name: SimpleIdentifier
+        token: int
+  colon: :
+  statements
+    BreakStatement
+      breakKeyword: break
+      semicolon: ;
+''');
+  }
+
   test_cast_insideCase() {
     _parse('''
 void f(x) {

diff --git a/pkg/analyzer/test/src/summary/resolved_ast_printer.dart b/pkg/analyzer/test/src/summary/resolved_ast_printer.dart
@@ -1438,6 +1438,14 @@ class ResolvedAstPrinter extends ThrowingAstVisitor<void> {
     });
   }
 
+  @override
+  void visitWhenClause(WhenClause node) {
+    _writeln('WhenClause');
+    _withIndent(() {
+      _writeNamedChildEntities(node);
+    });
+  }
+
   @override
   void visitWhileStatement(WhileStatement node) {
     _writeln('WhileStatement');