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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
//
//===----------------------------------------------------------------------===//
@testable import _StringProcessing
extension PEG {
// NOTE: We could have a collection-agnostic object code that we compile
// (provided no custom collection hooks are needed) to, and bind later.
// For now, we bind Input with the VM
public struct VM<Input: Collection> where Input.Element == Element {
typealias Core = PEGCore<Input>
typealias Instruction = Core.Instruction
var instructions: InstructionList<Instruction>
var enableTracing: Bool = false
}
}
extension PEG.VM {
struct Loader {
var functionLocations = Dictionary<FunctionId, InstructionAddress>()
// Need second pass to link functions and adjust branches
var functionFixups = Array<(InstructionAddress, FunctionId)>()
// var labelLocations = Dictionary<Code.Label, PC>()
}
static func load(_ code: Code) -> Self {
//
// Lower, layout, link, and load
//
// Layout (currently in `code` order)
var loweredInstructions = Array<Core.Instruction>()
// We will need to do a second pass to adjust function
// references
var functionLocations = Dictionary<FunctionId, InstructionAddress>()
var functionFixups = Array<(InstructionAddress, FunctionId)>()
func add(_ inst: Instruction) {
loweredInstructions.append(inst)
}
func addFunctionFixup(
_ inst: Instruction, _ f: FunctionId
) {
defer { add(inst) }
functionFixups.append((nextPC, f))
}
var nextPC: InstructionAddress { InstructionAddress(loweredInstructions.count) }
let invalidLoc = InstructionAddress(-1)
for funIdx in code.functions.indices {
functionLocations[FunctionId(funIdx)] = nextPC
let fun = code.functions[funIdx]
// We will need to do a second pass to adjust label
// references
var labelFixups = Array<(InstructionAddress, LabelId)>()
var labelLocations = Dictionary<LabelId, InstructionAddress>()
func addLabelFixup(_ inst: Instruction, _ l: LabelId) {
defer { add(inst) }
labelFixups.append((nextPC, l))
}
for inst in fun.instructions {
switch inst {
case .label(let l):
labelLocations[l] = nextPC
case .nop:
continue
case .comment(let s):
if emitComments { add(.comment(s)) }
case .consume(let n):
add(.consume(n))
case .element(let e):
add(.match(e))
case .set(let p):
add(.matchPredicate(p))
case .any:
add(.any)
// Lower labels
case .branch(let l):
addLabelFixup(.branch(to: invalidLoc), l)
case .condBranch(let cond, let l):
addLabelFixup(
.condBranch(condition: cond, to: invalidLoc), l)
case .save(let l):
addLabelFixup(.save(invalidLoc), l)
case .commit(let l):
add(.clear)
addLabelFixup(.branch(to: invalidLoc), l)
// Link calls
case .call(let f):
addFunctionFixup(.call(invalidLoc), f)
case .ret:
add(.ret)
case .startCapture:
fatalError()
case .endCapture:
fatalError()
// TODO:
case .accept:
add(.accept)
case .fail:
add(.fail)
case .abort:
add(.abort(reason: "ABORT!"))
}
}
// Fixup labels
for (pc, l) in labelFixups {
loweredInstructions[
pc.rawValue
].setPC(labelLocations[l]!)
}
}
// Fixup functions
for (pc, f) in functionFixups {
loweredInstructions[
pc.rawValue
].setPC(functionLocations[f]!)
}
return Self(instructions: InstructionList(loweredInstructions))
}
}
extension PEG.VM: CustomStringConvertible {
public var description: String {
instructions.indices.reduce("Instructions:\n") { result, idx in
result + "\(instructions.formatInstruction(idx, atCurrent: false, depth: 3))\n"
}
}
}
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