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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2021-2022 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
//
//===----------------------------------------------------------------------===//
/// State used when to pretty-printing regex ASTs.
public struct PrettyPrinter {
// Configuration
/// The maximum number number of levels, from the root of the tree,
/// at which to perform pattern conversion.
///
/// A `nil` value indicates that there is no maximum,
/// and pattern conversion always takes place.
public var maxTopDownLevels: Int?
/// The maximum number number of levels, from the leaf nodes of the tree,
/// at which to perform pattern conversion.
///
/// A `nil` value indicates that there is no maximum,
/// and pattern conversion always takes place.
public var minBottomUpLevels: Int?
/// The number of spaces used for indentation.
public var indentWidth = 2
// Internal state
// The output string we're building up
fileprivate var result = ""
// Whether next print needs to indent
fileprivate var startOfLine = true
// The indentation level
fileprivate var indentLevel = 0
// The current default quantification behavior
public var quantificationBehavior: AST.Quantification.Kind = .eager
// A stack of the current added inline matching options, e.g. (?s) and a
// boolean indicating true = added (?s) and false = removed (?-s).
public var inlineMatchingOptions: [([AST.MatchingOption], Bool)] = []
}
// MARK: - Raw interface
extension PrettyPrinter {
// This might be necessary if `fileprivate` above suppresses
// default struct inits.
public init(
maxTopDownLevels: Int? = nil,
minBottomUpLevels: Int? = nil
) {
self.maxTopDownLevels = maxTopDownLevels
self.minBottomUpLevels = minBottomUpLevels
}
/// Outputs a string directly, without termination or
/// indentation, and without updating any internal state.
///
/// This is the low-level interface to the pretty printer.
///
/// - Note: If `s` includes a newline, even at the end,
/// this method does not update any tracking state.
public mutating func output(_ s: String) {
result += s
}
/// Terminates a line, updating any relevant state.
public mutating func terminateLine() {
output("\n")
startOfLine = true
}
/// Indents a new line, if at the start of a line, otherwise
/// does nothing.
///
/// This function updates internal state.
public mutating func indent() {
guard startOfLine else { return }
let numCols = indentLevel * indentWidth
output(String(repeating: " ", count: numCols))
startOfLine = false
}
// Finish, flush, and clear.
//
// - Returns: The rendered output.
public mutating func finish() -> String {
defer { result = "" }
return result
}
public var depth: Int { indentLevel }
}
// MARK: - Pretty-print interface
extension PrettyPrinter {
/// Print out a new entry.
///
/// This method indents `s`, updates any internal state,
/// and terminates the current line.
public mutating func print(_ s: String) {
indent()
output("\(s)")
terminateLine()
}
/// Prints out a new entry by invoking `f` until it returns `nil`.
///
/// This method indents `s`, updates any internal state,
/// and terminates the current line.
public mutating func printLine(_ f: () -> String?) {
// TODO: What should we do if `f` never returns non-nil?
indent()
while let s = f() {
output(s)
}
terminateLine()
}
/// Executes `f` at one increased level of indentation.
public mutating func printIndented(
_ f: (inout Self) -> ()
) {
self.indentLevel += 1
f(&self)
self.indentLevel -= 1
}
/// Executes `f` inside an indented block, which has a header
/// and delimiters.
public mutating func printBlock(
_ header: String,
startDelimiter: String = "{",
endDelimiter: String = "}",
_ f: (inout Self) -> ()
) {
print("\(header) \(startDelimiter)")
printIndented(f)
print(endDelimiter)
}
/// Pushes the list of matching options to the current stack of other matching
/// options and increases the indentation level by 1.
public mutating func pushMatchingOptions(
_ options: [AST.MatchingOption],
isAdded: Bool
) {
indentLevel += 1
inlineMatchingOptions.append((options, isAdded))
}
/// Pops the most recent list of matching options from the printer and
/// decreases the indentation level by 1.
public mutating func popMatchingOptions() -> ([AST.MatchingOption], Bool) {
indentLevel -= 1
return inlineMatchingOptions.removeLast()
}
}
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