jasonwyatt/KWasm

/*
 * Copyright 2020 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */

package kwasm.validation.instruction.memory

import kwasm.ast.instruction.MemoryInstruction
import kwasm.ast.type.ValueType
import kwasm.validation.FunctionBodyValidationVisitor
import kwasm.validation.ValidationContext

/**
 * Validator of [MemoryInstruction.Size] nodes.
 *
 * From
 * [the docs](https://webassembly.github.io/spec/core/valid/instructions.html#memory-instructions):
 *
 * * The memory `C.mems[0]` must be defined in the context.
 * * Then the instruction is valid with type `[] => \[i32]`.
 */
object SizeValidator : FunctionBodyValidationVisitor<MemoryInstruction.Size> {
    override fun visit(
        node: MemoryInstruction.Size,
        context: ValidationContext.FunctionBody
    ): ValidationContext.FunctionBody {
        context.validateMemoryExists()
        return context.pushStack(ValueType.I32)
    }
}