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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#if swift(>=6)
internal import SwiftSyntax
#else
import SwiftSyntax
#endif
/// Maintains and validates information about all operators in a Swift program.
///
/// The operator table keep track of the various operator and precedence group
/// declarations within a program. Its core operations involve processing the
/// operator and precedence group declarations from a source tree into a
/// semantic representation, validating the correctness of those declarations,
/// and "folding" sequence expression syntax into a structured expression
/// syntax tree.
public struct OperatorTable: Sendable {
var precedenceGraph: PrecedenceGraph = .init()
var infixOperators: [OperatorName: Operator] = [:]
var prefixOperators: [OperatorName: Operator] = [:]
var postfixOperators: [OperatorName: Operator] = [:]
public init() {}
/// Initialize the operator precedence instance with a given set of
/// operators and precedence groups.
@_optimize(none)
public init(
precedenceGroups: [PrecedenceGroup],
operators: [Operator],
errorHandler: OperatorErrorHandler = { throw $0 }
) rethrows {
for group in precedenceGroups {
try record(group, errorHandler: errorHandler)
}
for op in operators {
try record(op, errorHandler: errorHandler)
}
}
/// Record the operator in the given operator array.
private func record(
_ op: Operator,
in table: inout [OperatorName: Operator],
errorHandler: OperatorErrorHandler = { throw $0 }
) rethrows {
if let existing = table[op.name] {
try errorHandler(.operatorAlreadyExists(existing: existing, new: op))
} else {
table[op.name] = op
}
}
/// Record the operator.
mutating func record(
_ op: Operator,
errorHandler: OperatorErrorHandler = { throw $0 }
) rethrows {
switch op.kind {
case .infix:
return try record(op, in: &infixOperators, errorHandler: errorHandler)
case .prefix:
return try record(op, in: &prefixOperators, errorHandler: errorHandler)
case .postfix:
return try record(op, in: &postfixOperators, errorHandler: errorHandler)
}
}
/// Record the precedence group.
mutating func record(
_ group: PrecedenceGroup,
errorHandler: OperatorErrorHandler = { throw $0 }
) rethrows {
try precedenceGraph.add(group, errorHandler: errorHandler)
}
}
extension OperatorTable {
/// Returns the ``Operator`` corresponding to the given infix operator, or
/// `nil` if it is not defined in the operator table.
public func infixOperator(named operatorName: OperatorName) -> Operator? {
return infixOperators[operatorName]
}
/// Returns the ``Operator`` corresponding to the given prefix operator, or
/// `nil` if it is not defined in the operator table.
public func prefixOperator(named operatorName: OperatorName) -> Operator? {
return prefixOperators[operatorName]
}
/// Returns the ``Operator`` corresponding to the given prefix operator, or
/// `nil` if it is not defined in the operator table.
public func postfixOperator(named operatorName: OperatorName) -> Operator? {
return postfixOperators[operatorName]
}
/// Look for the precedence group corresponding to the given operator.
func lookupOperatorPrecedenceGroupName(
_ operatorName: OperatorName,
referencedFrom syntax: Syntax,
errorHandler: OperatorErrorHandler = { throw $0 }
) rethrows -> PrecedenceGroupName? {
guard let op = infixOperator(named: operatorName) else {
try errorHandler(
.missingOperator(operatorName, referencedFrom: syntax)
)
return nil
}
return op.precedenceGroup
}
}
extension OperatorTable: CustomStringConvertible {
/// The description of an operator table is the source code that produces it.
public var description: String {
var result = ""
// Turn all of the dictionary values into their string representations.
func add<Key: Comparable, Value: CustomStringConvertible>(
_ dict: [Key: Value]
) {
if dict.isEmpty {
return
}
result.append(
contentsOf: dict.sorted { $0.key < $1.key }
.map { $0.value.description }
.joined(separator: "\n")
)
result += "\n"
}
add(precedenceGraph.precedenceGroups)
add(prefixOperators)
add(postfixOperators)
add(infixOperators)
return result
}
}
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