platform/lib/src/language/parser.dart

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library graphql_parser.language.parser;
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import 'ast/ast.dart';
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import 'syntax_error.dart';
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import 'token.dart';
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import 'token_type.dart';
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class Parser {
Token _current;
int _index = -1;
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final List<Token> tokens;
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Parser(this.tokens);
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Token get current => _current;
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bool next(TokenType type) {
if (peek()?.type == type) {
_current = tokens[++_index];
return true;
}
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return false;
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}
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Token peek() {
if (_index < tokens.length - 1) {
return tokens[_index + 1];
}
return null;
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}
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DocumentContext parseDocument() {}
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FragmentDefinitionContext parseFragmentDefinition() {}
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FragmentSpreadContext parseFragmentSpread() {}
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InlineFragmentContext parseInlineFragment() {}
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SelectionSetContext parseSelectionSet() {}
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SelectionContext parseSelection() {}
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FieldContext parseField() {}
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FieldNameContext parseFieldName() {}
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AliasContext parseAlias() {}
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VariableDefinitionsContext parseVariableDefinitions() {}
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VariableDefinitionContext parseVariableDefinition() {}
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List<DirectiveContext> parseDirectives() {}
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DirectiveContext parseDirective() {
if (next(TokenType.ARROBA)) {
var ARROBA = current;
if (next(TokenType.NAME)) {
var NAME = current;
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if (next(TokenType.COLON)) {
var COLON = current;
var val = parseValueOrVariable();
if (val != null)
return new DirectiveContext(
ARROBA, NAME, COLON, null, null, null, val);
else
throw new SyntaxError.fromSourceLocation(
'Expected value or variable in directive after colon.',
COLON.span.end);
} else if (next(TokenType.LPAREN)) {
var LPAREN = current;
var arg = parseArgument();
if (arg != null) {
if (next(TokenType.RPAREN)) {
return new DirectiveContext(
ARROBA, NAME, null, LPAREN, current, arg, null);
} else
throw new SyntaxError.fromSourceLocation(
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'Expected \')\'', arg.valueOrVariable.span.end);
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} else
throw new SyntaxError.fromSourceLocation(
'Expected argument in directive.', LPAREN.span.end);
} else
return new DirectiveContext(
ARROBA, NAME, null, null, null, null, null);
} else
throw new SyntaxError.fromSourceLocation(
'Expected name for directive.', ARROBA.span.end);
} else
return null;
}
ArgumentContext parseArgument() {
if (next(TokenType.NAME)) {
var NAME = current;
if (next(TokenType.COLON)) {
var COLON = current;
var val = parseValueOrVariable();
if (val != null)
return new ArgumentContext(NAME, COLON, val);
else
throw new SyntaxError.fromSourceLocation(
'Expected value or variable in argument.', COLON.span.end);
} else
throw new SyntaxError.fromSourceLocation(
'Expected colon after name in argument.', NAME.span.end);
} else
return null;
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}
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ValueOrVariableContext parseValueOrVariable() {
var value = parseValue();
if (value != null)
return new ValueOrVariableContext(value, null);
else {
var variable = parseVariable();
if (variable != null)
return new ValueOrVariableContext(null, variable);
else
return null;
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}
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}
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VariableContext parseVariable() {
if (next(TokenType.DOLLAR)) {
var DOLLAR = current;
if (next(TokenType.NAME))
return new VariableContext(DOLLAR, current);
else
throw new SyntaxError.fromSourceLocation(
'Expected name for variable; found a lone "\$" instead.',
DOLLAR.span.end);
} else
return null;
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}
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DefaultValueContext parseDefaultValue() {}
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TypeConditionContext parseTypeCondition() {}
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ValueContext parseValue() {
return parseStringValue() ??
parseNumberValue() ??
parseBooleanValue() ??
parseArrayValue();
}
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StringValueContext parseStringValue() =>
next(TokenType.STRING) ? new StringValueContext(current) : null;
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NumberValueContext parseNumberValue() =>
next(TokenType.NUMBER) ? new NumberValueContext(current) : null;
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BooleanValueContext parseBooleanValue() =>
next(TokenType.BOOLEAN) ? new BooleanValueContext(current) : null;
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ArrayValueContext parseArrayValue() {
if (next(TokenType.LBRACKET)) {
var LBRACKET = current;
List<ValueContext> values = [];
ValueContext value = parseValue();
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while (value != null) {
values.add(value);
if (next(TokenType.COMMA)) {
value = parseValue();
} else
break;
}
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if (next(TokenType.RBRACKET)) {
return new ArrayValueContext(LBRACKET, current)..values.addAll(values);
} else
throw new SyntaxError.fromSourceLocation(
'Unterminated array literal.', LBRACKET.span.end);
} else
return null;
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}
}