ucl/cmdlang/inst.go

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package cmdlang
import (
"context"
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"errors"
"fmt"
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"io"
"os"
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"strings"
)
type Inst struct {
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out io.Writer
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rootEC *evalCtx
}
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type InstOption func(*Inst)
func WithOut(out io.Writer) InstOption {
return func(i *Inst) {
i.out = out
}
}
func New(opts ...InstOption) *Inst {
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rootEC := evalCtx{}
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rootEC.addCmd("echo", invokableFunc(echoBuiltin))
rootEC.addCmd("set", invokableFunc(setBuiltin))
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rootEC.addCmd("toUpper", invokableStreamFunc(toUpperBuiltin))
rootEC.addCmd("cat", invokableFunc(catBuiltin))
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rootEC.addMacro("if", macroFunc(ifBuiltin))
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//rootEC.addCmd("testTimebomb", invokableStreamFunc(errorTestBuiltin))
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rootEC.setVar("hello", strObject("world"))
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inst := &Inst{
out: os.Stdout,
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rootEC: &rootEC,
}
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for _, opt := range opts {
opt(inst)
}
return inst
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}
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func (inst *Inst) Out() io.Writer {
if inst.out == nil {
return os.Stdout
}
return inst.out
}
func (inst *Inst) Eval(ctx context.Context, expr string) (any, error) {
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res, err := inst.eval(ctx, expr)
if err != nil {
return nil, err
}
goRes, ok := toGoValue(res)
if !ok {
return nil, errors.New("result not convertable to go")
}
return goRes, nil
}
func (inst *Inst) eval(ctx context.Context, expr string) (object, error) {
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ast, err := parse(strings.NewReader(expr))
if err != nil {
return nil, err
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}
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eval := evaluator{inst: inst}
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return eval.evalScript(ctx, inst.rootEC, ast)
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}
func (inst *Inst) EvalAndDisplay(ctx context.Context, expr string) error {
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res, err := inst.eval(ctx, expr)
if err != nil {
return err
}
return inst.display(ctx, res)
}
func (inst *Inst) display(ctx context.Context, res object) (err error) {
switch v := res.(type) {
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case nil:
if _, err = fmt.Fprintln(inst.out, "(nil)"); err != nil {
return err
}
case stream:
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return forEach(v, func(o object, _ int) error { return inst.display(ctx, o) })
default:
if _, err = fmt.Fprintln(inst.out, v.String()); err != nil {
return err
}
}
return nil
}