// ExpectResult check the evaluation of a string with an expected result.
// More importantly though, does the steps to evaluate a string:
// 1. Parse expression using parser.ParseExpr (go/parser)
// 2. Type check expression using evalCheckExpr (0xfaded/eval)
// 3. run eval.EvalExpr (0xfaded/eval)
func ExampleFullApi() {
expr := `fmt.Sprintf("%s %d", constant1, add(var1, 1) + 1)`
env := makeEnv() // Create evaluation environment
if e, err := parser.ParseExpr(expr); err != nil {
fmt.Printf("Failed to parse expression '%s' (%v)\n", expr, err)
} else if cexpr, errs := eval.CheckExpr(e, env); len(errs) != 0 {
fmt.Printf("Error checking expression '%s' (%v)\n", expr, errs)
} else if results, err := eval.EvalExpr(cexpr, env); err != nil {
fmt.Printf("Panic evaluating expression '%s' (%v)\n", expr, err)
} else {
fmt.Printf("Expression '%s' yielded '%+v'\n", expr, results[0].Interface())
}
}
func expectResult(expr string, env eval.Env, expected interface{}) {
if e, err := parser.ParseExpr(expr); err != nil {
fmt.Printf("Failed to parse expression '%s' (%v)\n", expr, err)
return
} else if cexpr, errs := eval.CheckExpr(e, env); len(errs) != 0 {
fmt.Printf("Error checking expression '%s' (%v)\n", expr, errs)
} else if results, err := eval.EvalExpr(cexpr, env); err != nil {
fmt.Printf("Error evaluating expression '%s' (%v)\n", expr, err)
return
} else {
fmt.Printf("Expression '%s' yielded '%+v', expected '%+v'\n",
expr, results[0].Interface(), expected)
}
}
// REPL is the a read, eval, and print loop.
func REPL(env *eval.SimpleEnv) {
var err error
// A place to store result values of expressions entered
// interactively
results := make([]interface{}, 0, 10)
env.Vars["results"] = reflect.ValueOf(&results)
exprs := 0
in := bufio.NewReader(os.Stdin)
line, err := readline("go> ", in)
for line != "quit" {
if err != nil {
if err == io.EOF {
break
}
panic(err)
}
if expr, err := parser.ParseExpr(line); err != nil {
if pair := eval.FormatErrorPos(line, err.Error()); len(pair) == 2 {
fmt.Println(pair[0])
fmt.Println(pair[1])
}
fmt.Printf("parse error: %s\n", err)
} else if cexpr, errs := eval.CheckExpr(expr, env); len(errs) != 0 {
for _, cerr := range errs {
fmt.Printf("check error: %v\n", cerr)
}
} else if vals, err := eval.EvalExpr(cexpr, env); err != nil {
fmt.Printf("panic: %s\n", err)
} else if len(vals) == 0 {
fmt.Printf("Kind=Slice\nvoid\n")
} else if len(vals) == 1 {
value := (vals)[0]
if value.IsValid() {
kind := value.Kind().String()
typ := value.Type().String()
if typ != kind {
fmt.Printf("Kind = %v\n", kind)
fmt.Printf("Type = %v\n", typ)
} else {
fmt.Printf("Kind = Type = %v\n", kind)
}
fmt.Printf("results[%d] = %s\n", exprs, eval.Inspect(value))
exprs += 1
results = append(results, (vals)[0].Interface())
} else {
fmt.Printf("%s\n", value)
}
} else {
fmt.Printf("Kind = Multi-Value\n")
size := len(vals)
for i, v := range vals {
fmt.Printf("%s", eval.Inspect(v))
if i < size-1 {
fmt.Printf(", ")
}
}
fmt.Printf("\n")
exprs += 1
results = append(results, vals)
}
line, err = readline("go> ", in)
}
}