92 lines
2.5 KiB
Go
92 lines
2.5 KiB
Go
/*
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Serene --- Yet an other Lisp
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Copyright (c) 2020 Sameer Rahmani <lxsameer@gnu.org>
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This program 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 2 of the License.
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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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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package core
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// Instructions Implementation:
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// * Instructions are expressions as well but they are not doing
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// anything special by themselves.
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// * We need them to be expressions because we need to process
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// them as part of the evaluation loop
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// * We use instructions as nodes in the AST to instruct Serene
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// to do specific tasks after rewriting the AST. For example
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// `PopStack` instructs Serene to simply pop a call from the
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// call stack.
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// * Instructions doesn't return a value and should not alter
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// the return value of the eval loop. But they might interrupt
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// the loop by raising an error `IError`.
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import (
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"fmt"
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"serene-lang.org/bootstrap/pkg/ast"
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"serene-lang.org/bootstrap/pkg/hash"
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)
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type instructionType int
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// Instruction types
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const (
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// Pop a function from the call stack. We use this
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// instruction at the end of function bodies. So
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// function bodies will clean up after themselves
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PopStack instructionType = iota
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)
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type Instruction struct {
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// Just to be compatible with IExpr ---
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Node
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ExecutionScope
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// ------------------------------------
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Type instructionType
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}
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func (n *Instruction) GetType() ast.NodeType {
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return ast.Instruction
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}
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func (n *Instruction) String() string {
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return fmt.Sprintf("<instruction:%d>", n.Type)
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}
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func (n *Instruction) ToDebugStr() string {
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return n.String()
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}
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func (n *Instruction) Hash() uint32 {
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bytes := []byte(fmt.Sprintf("%d", n.Type))
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return hash.Of(append([]byte{byte(ast.Instruction)}, bytes...))
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}
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func MakeStackPop(rt *Runtime) IExpr {
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return &Instruction{
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Type: PopStack,
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}
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}
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// ProcessInstruction is the main function to process instructions
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func ProcessInstruction(rt *Runtime, form *Instruction) IError {
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switch form.Type {
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case PopStack:
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rt.Stack.Pop()
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return nil
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default:
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panic(fmt.Sprintf("Unknown instruction: '%d'", form.Type))
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}
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}
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