97 lines
1.9 KiB
Swift
97 lines
1.9 KiB
Swift
//
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// Parser.swift
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// damus
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//
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// Created by William Casarin on 2022-05-04.
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//
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import Foundation
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class Parser {
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var pos: Int
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var str: String
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init(pos: Int, str: String) {
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self.pos = pos
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self.str = str
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}
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}
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func consume_until(_ p: Parser, match: (Character) -> Bool) -> Bool {
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var i: Int = 0
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let sub = substring(p.str, start: p.pos, end: p.str.count)
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for c in sub {
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if match(c) {
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p.pos += i
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return true
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}
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i += 1
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}
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return false
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}
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func substring(_ s: String, start: Int, end: Int) -> Substring {
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let ind = s.index(s.startIndex, offsetBy: start)
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let end = s.index(s.startIndex, offsetBy: end)
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return s[ind..<end]
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}
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func parse_str(_ p: Parser, _ s: String) -> Bool {
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if p.pos + s.count > p.str.count {
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return false
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}
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let sub = substring(p.str, start: p.pos, end: p.pos + s.count)
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if sub == s {
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p.pos += s.count
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return true
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}
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return false
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}
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func parse_char(_ p: Parser, _ c: Character) -> Bool {
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if p.pos >= p.str.count {
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return false
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}
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let ind = p.str.index(p.str.startIndex, offsetBy: p.pos)
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if p.str[ind] == c {
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p.pos += 1
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return true
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}
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return false
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}
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func parse_digit(_ p: Parser) -> Int? {
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let ind = p.str.index(p.str.startIndex, offsetBy: p.pos)
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if let c = p.str[ind].unicodeScalars.first {
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let d = Int(c.value) - 48
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if d >= 0 && d < 10 {
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p.pos += 1
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return Int(d)
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}
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}
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return 0
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}
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func parse_hex_char(_ p: Parser) -> Character? {
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let ind = p.str.index(p.str.startIndex, offsetBy: p.pos)
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if let c = p.str[ind].unicodeScalars.first {
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// hex chars
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let d = c.value
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if (d >= 48 && d <= 57) || (d >= 97 && d <= 102) || (d >= 65 && d <= 70) {
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p.pos += 1
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return p.str[ind]
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}
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}
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return nil
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}
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