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/// A location in a WAT source file.
public struct Location: Equatable, CustomDebugStringConvertible {
let index: Lexer.Index
let source: String.UnicodeScalarView
init(at index: Lexer.Index, in source: String.UnicodeScalarView) {
self.index = index
self.source = source
}
public static func == (lhs: Location, rhs: Location) -> Bool {
return lhs.index == rhs.index
}
public var debugDescription: String {
return "Location\(sourceLocation(at: index, in: source))"
}
/// Computes the line and column of the location in the source file.
/// - Returns: The line and column of the location. Line is 1-indexed and column is 0-indexed.
public func computeLineAndColumn() -> (line: Int, column: Int) {
return sourceLocation(at: index, in: source)
}
}
/// Returns the location of the given index in the source
/// - Parameters:
/// - index: The index in the source
/// - source: The source string
/// - Returns: The location of the index in line-column style. Line is 1-indexed and column is 0-indexed.
func sourceLocation(at index: Lexer.Index, in source: String.UnicodeScalarView) -> (line: Int, column: Int) {
let slice = source[..<index]
let lineNo = slice.split(separator: "\n", omittingEmptySubsequences: false).count
let columnNo: Int
if let lastNewlineIndex = slice.lastIndex(of: "\n") {
columnNo = slice.distance(from: lastNewlineIndex, to: index)
} else {
// The current position is the first line of the input
columnNo = slice.distance(from: slice.startIndex, to: index)
}
return (line: lineNo, column: columnNo)
}
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