Will Hawkins
122 lines
3.1 KiB
Swift
122 lines
3.1 KiB
Swift
// p4rse, Copyright 2026, Will Hawkins
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//
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// This file is part of p4rse.
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//
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// This file is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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public struct Scope<T>: CustomStringConvertible {
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var symbols: [Identifier: T] = Dictionary()
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public init() {}
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public var description: String {
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var result = String()
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for (k, v) in symbols {
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result += "\(k): \(v)\n"
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}
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return result
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}
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public var count: Int {
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symbols.count
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}
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public func lookup(identifier: Identifier) -> T? {
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if let symbol = symbols[identifier] {
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return symbol
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}
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return .none
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}
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public func declare(identifier: Identifier, withValue value: T) -> Scope {
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var s = self
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s.symbols[identifier] = value
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return s
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}
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}
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public struct Scopes<T>: CustomStringConvertible {
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var scopes: [Scope<T>] = Array()
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public init() {}
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init(withScopes scopes: [Scope<T>]) {
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self.scopes = scopes
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}
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public func enter() -> Scopes {
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var new_scopes = scopes
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new_scopes.append(Scope())
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return Scopes(withScopes: new_scopes)
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}
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public func exit() -> Scopes {
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var old_scopes = scopes
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_ = old_scopes.popLast()
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return Scopes(withScopes: old_scopes)
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}
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public var description: String {
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var result = String()
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for s in scopes {
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result += "LexicalScope:\n\(s)\n"
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}
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return result
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}
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public var current: Scope<T>? {
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scopes.last
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}
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public func set(identifier: Identifier, withValue value: T) -> Scopes {
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var scopes = self.scopes
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var scopes_to_read: [Scope<T>] = Array()
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// Find the scope that has `identifier`
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while let scope = scopes.popLast() {
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if scope.lookup(identifier: identifier) != nil {
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// Update that scope and add it to scopes
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scopes.append(scope.declare(identifier: identifier, withValue: value))
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break
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} else {
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// If there was no match, we'll put it back
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scopes_to_read.append(scope)
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}
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}
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return Scopes<T>(withScopes: (scopes + scopes_to_read))
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}
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public func declare(identifier: Identifier, withValue value: T) -> Scopes {
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var s = self
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if let scope = s.scopes.popLast() {
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s.scopes.append(scope.declare(identifier: identifier, withValue: value))
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}
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return s
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}
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public func lookup(identifier: Identifier) -> Result<T> {
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for scope in scopes {
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if let vari = scope.lookup(identifier: identifier) {
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return .Ok(vari)
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}
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}
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return .Error(Error(withMessage: "Cannot find \(identifier) in lexical scope."))
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}
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public var count: Int {
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scopes.count
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}
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}
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