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Feat: Allow member access on literal expressions such as [1,2,3].length #36

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Feat: Allow member access on literal expressions such as [1,2,3].length #36

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14 changes: 7 additions & 7 deletions lib/src/parser.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ class ExpressionParser {
(l) => l[1] == null
? l[0]
: ConditionalExpression(l[0], l[1][0], l[1][1])));
token.set((literal | unaryExpression | variable).cast<Expression>());
token.set((unaryExpression | variable).cast<Expression>());
}

// Gobbles only identifiers
Expand Down Expand Up @@ -99,6 +99,10 @@ class ExpressionParser {
mapLiteral)
.cast();

Parser<Expression> get _primary =>
(literal | group | thisExpression | identifier.map((v) => Variable(v)))
.cast();

// An individual part of a binary expression:
// e.g. `foo.bar(baz)`, `1`, `'abc'`, `(a % 2)` (because it's in parenthesis)
final SettableParser<Expression> token = undefined<Expression>();
Expand Down Expand Up @@ -207,9 +211,8 @@ class ExpressionParser {
// e.g. `foo`, `bar.baz`, `foo['bar'].baz`
// It also gobbles function calls:
// e.g. `Math.acos(obj.angle)`
Parser<Expression> get variable => groupOrIdentifier
.seq((memberArgument.cast() | indexArgument | callArgument).star())
.map((l) {
Parser<Expression> get variable =>
_primary.seq((memberArgument.cast() | indexArgument | callArgument).star()).map((l) {
var a = l[0] as Expression;
var b = l[1] as List;
return b.fold(a, (Expression object, argument) {
Expand All @@ -234,9 +237,6 @@ class ExpressionParser {
Parser<Expression> get group =>
(char('(') & expression.trim() & char(')')).pick(1).cast();

Parser<Expression> get groupOrIdentifier =>
(group | thisExpression | identifier.map((v) => Variable(v))).cast();

Parser<Identifier> get memberArgument =>
(char('.') & identifier).pick(1).cast();

Expand Down
9 changes: 9 additions & 0 deletions test/expressions_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -254,6 +254,15 @@ void main() {
});

group('member expressions', () {
test('literal members', () {
var evaluator = ExpressionEvaluator(memberAccessors: [
MemberAccessor<List>({'length': (v) => v.length}),
MemberAccessor<String>({'length': (v) => v.length})
]);
expect(evaluator.eval(Expression.parse('[1,2,3].length'), {}), 3);
expect(evaluator.eval(Expression.parse("'hello'.length"), {}), 5);
});

test('toString member', () {
var evaluator = ExpressionEvaluator(memberAccessors: [
MemberAccessor<Object?>({'toString': (v) => v.toString})
Expand Down