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-rw-r--r--cmd/interpreter/main.go4
-rw-r--r--cmd/repl/main.go3
-rw-r--r--ell/ell.go297
3 files changed, 136 insertions, 168 deletions
diff --git a/cmd/interpreter/main.go b/cmd/interpreter/main.go
index bd70af3..e0001a2 100644
--- a/cmd/interpreter/main.go
+++ b/cmd/interpreter/main.go
@@ -53,9 +53,7 @@ func main() {
for i := 2; i < len(os.Args); i++ {
args = append(args, *ell.NewString(os.Args[i]))
}
-
- var result []ell.V
- if !L.EvalBlock(program, args, &result) {
+ if _, ok := L.EvalBlock(program, args); !ok {
fmt.Printf("%s: %s\n", "runtime error", L.Error)
}
}
diff --git a/cmd/repl/main.go b/cmd/repl/main.go
index b1bb413..3511931 100644
--- a/cmd/repl/main.go
+++ b/cmd/repl/main.go
@@ -29,8 +29,7 @@ import (
)
func run(L *ell.Ell, program []ell.V) {
- var result []ell.V
- if !L.EvalBlock(program, nil, &result) {
+ if result, ok := L.EvalBlock(program, nil); !ok {
fmt.Printf("\x1b[31m%s: %s\x1b[0m\n", "runtime error", L.Error)
L.Error = ""
} else {
diff --git a/ell/ell.go b/ell/ell.go
index 3117918..af4c407 100644
--- a/ell/ell.go
+++ b/ell/ell.go
@@ -346,7 +346,7 @@ func printBlock(w io.Writer, list *V) bool {
_, _ = w.Write([]byte{' '})
PrintSeq(w, sublist[0].List)
for _, subsub := range sublist[1:] {
- _, _ = w.Write([]byte{';', ' '})
+ _, _ = w.Write([]byte("; "))
PrintSeq(w, subsub.List)
}
_, _ = w.Write([]byte{' '})
@@ -391,13 +391,12 @@ func PrintV(w io.Writer, v *V) {
// PrintSeq serializes a sequence of values to the given writer.
func PrintSeq(w io.Writer, seq []V) {
- if len(seq) < 1 {
- return
- }
- PrintV(w, &seq[0])
- for _, v := range seq[1:] {
- _, _ = w.Write([]byte{' '})
- PrintV(w, &v)
+ if len(seq) > 0 {
+ PrintV(w, &seq[0])
+ for _, v := range seq[1:] {
+ _, _ = w.Write([]byte{' '})
+ PrintV(w, &v)
+ }
}
}
@@ -451,16 +450,15 @@ func (p *Parser) skipNL() {
}
func parsePrefixList(seq []V, name string) *V {
- prefix := []V{*NewString(name)}
- return NewList(append(prefix, seq...))
+ return NewList(append([]V{*NewString(name)}, seq...))
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
func (p *Parser) parseV() *V {
- var seq []V
-
p.skipNL()
+
+ var seq []V
switch {
case p.accept(tString):
return NewString(string(p.lexer.buf))
@@ -495,7 +493,6 @@ func (p *Parser) parseV() *V {
func (p *Parser) parseLine() *V {
var seq []V
-
for p.peek() != tRBrace && p.peek() != tAbort {
if !p.accept(tNewline) {
seq = append(seq, *p.parseV())
@@ -534,7 +531,7 @@ func (p *Parser) Run() (seq []V, err error) {
// --- Runtime -----------------------------------------------------------------
// Handler is a Go handler for an Ell function.
-type Handler func(*Ell, []V, *[]V) bool
+type Handler func(ell *Ell, args []V) (result []V, ok bool)
// Ell is an interpreter context.
type Ell struct {
@@ -590,10 +587,11 @@ func (ell *Ell) Set(name string, v *V) {
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-// Errorf sets an error message in the interpreter context and returns false.
-func (ell *Ell) Errorf(format string, args ...interface{}) bool {
+// Errorf sets an error message in the interpreter context and returns an empty
+// sequence and false.
+func (ell *Ell) Errorf(format string, args ...interface{}) ([]V, bool) {
ell.Error = fmt.Sprintf(format, args...)
- return false
+ return nil, false
}
func (ell *Ell) canModifyError() bool {
@@ -602,92 +600,89 @@ func (ell *Ell) canModifyError() bool {
return ell.Error == "" || ell.Error[0] != '_'
}
-func (ell *Ell) evalArgs(args []V, result *[]V) bool {
+func (ell *Ell) evalArgs(args []V) (result []V, ok bool) {
for i, arg := range args {
- var evaluated []V
- // Arguments should not evaporate, default to a nil value.
- if !ell.evalStatement(&arg, &evaluated) {
+ evaluated, ok := ell.evalStatement(&arg)
+ if !ok {
// Once the code flows like this, at least make some use of it.
if ell.canModifyError() {
ell.Errorf("(argument %d) -> %s", i, ell.Error)
}
- *result = nil
- return false
+ return nil, false
}
+ // Arguments should not evaporate, default to a nil value.
if len(evaluated) < 1 {
evaluated = []V{*NewList(nil)}
}
- *result = append(*result, evaluated[0])
+ result = append(result, evaluated[0])
}
- return true
+ return result, true
}
-func (ell *Ell) evalNative(name string, args []V, result *[]V) bool {
+func (ell *Ell) evalNative(name string, args []V) (result []V, ok bool) {
fn := ell.Native[name]
if fn == nil {
return ell.Errorf("unknown function")
}
-
- var arguments []V
- return ell.evalArgs(args, &arguments) && fn(ell, arguments, result)
+ if arguments, ok := ell.evalArgs(args); ok {
+ return fn(ell, arguments)
+ }
+ return nil, false
}
-func (ell *Ell) evalResolved(body *V, args []V, result *[]V) bool {
+func (ell *Ell) evalResolved(body *V, args []V) (result []V, ok bool) {
// Resolving names recursively could be pretty fatal, let's not do that.
if body.Type == VTypeString {
- *result = []V{*body.Clone()}
- return true
+ return []V{*body}, true
}
- var arguments []V
- return ell.evalArgs(args, &arguments) &&
- ell.EvalBlock(body.List, arguments, result)
+ if arguments, ok := ell.evalArgs(args); ok {
+ return ell.EvalBlock(body.List, arguments)
+ }
+ return nil, false
}
-func (ell *Ell) evalValue(body []V, result *[]V) bool {
+func (ell *Ell) evalValue(body []V) (result []V, ok bool) {
args := body[1:]
if body[0].Type == VTypeString {
name := body[0].String
if name == "block" {
if len(args) > 0 {
- *result = []V{*NewList(CloneSeq(args))}
+ result = []V{*NewList(CloneSeq(args))}
}
- return true
+ return result, true
}
if body := ell.Get(name); body != nil {
- return ell.evalResolved(body, args, result)
+ return ell.evalResolved(body, args)
}
- return ell.evalNative(name, args, result)
+ return ell.evalNative(name, args)
}
// When someone tries to call a block directly, we must evaluate it;
// e.g. something like `{ choose [@f1 @f2 @f3] } arg1 arg2 arg3`.
- var evaluated []V
- if !ell.evalStatement(&body[0], &evaluated) {
- return false
+ if evaluated, ok := ell.evalStatement(&body[0]); !ok {
+ return nil, false
+ } else if len(evaluated) > 0 {
+ return ell.evalResolved(&evaluated[0], args)
}
// It might a bit confusing that this doesn't evaluate arguments
// but neither does "block" and there's nothing to do here.
- if len(evaluated) < 1 {
- return true
- }
- return ell.evalResolved(&evaluated[0], args, result)
+ return nil, true
}
-func (ell *Ell) evalStatement(statement *V, result *[]V) bool {
+func (ell *Ell) evalStatement(statement *V) (result []V, ok bool) {
if statement.Type == VTypeString {
- *result = []V{*statement.Clone()}
- return true
+ return []V{*statement}, true
}
// Executing a nil value results in no value. It's not very different from
// calling a block that returns no value--it's for our callers to resolve.
- if len(statement.List) < 1 ||
- ell.evalValue(statement.List, result) {
- return true
+ if len(statement.List) < 1 {
+ return nil, true
+ }
+ if result, ok = ell.evalValue(statement.List); ok {
+ return
}
-
- *result = nil
name := "(block)"
if statement.List[0].Type == VTypeString {
@@ -697,7 +692,7 @@ func (ell *Ell) evalStatement(statement *V, result *[]V) bool {
if ell.canModifyError() {
ell.Errorf("%s -> %s", name, ell.Error)
}
- return false
+ return nil, false
}
func argsToScope(args []V) map[string]V {
@@ -710,38 +705,34 @@ func argsToScope(args []V) map[string]V {
// EvalBlock executes a block and returns whatever the last statement returned,
// eats args.
-func (ell *Ell) EvalBlock(body []V, args []V, result *[]V) bool {
+func (ell *Ell) EvalBlock(body []V, args []V) (result []V, ok bool) {
ell.scopes = append(ell.scopes, argsToScope(args))
- ok := true
+ ok = true
for _, stmt := range body {
- *result = nil
- if ok = ell.evalStatement(&stmt, result); !ok {
+ if result, ok = ell.evalStatement(&stmt); !ok {
break
}
}
ell.scopes = ell.scopes[:len(ell.scopes)-1]
- return ok
+ return result, ok
}
// --- Standard library --------------------------------------------------------
// EvalAny evaluates any value and appends to the result.
-func EvalAny(ell *Ell, body *V, arg *V, result *[]V) bool {
+func EvalAny(ell *Ell, body *V, arg *V) (result []V, ok bool) {
if body.Type == VTypeString {
- *result = []V{*body.Clone()}
- return true
+ return []V{*body}, true
}
var args []V
if arg != nil {
args = append(args, *arg.Clone())
}
- var res []V
- if !ell.EvalBlock(body.List, args, &res) {
- return false
+ if res, ok := ell.EvalBlock(body.List, args); ok {
+ return res, true
}
- *result = append(*result, res...)
- return true
+ return nil, false
}
// NewNumber creates a new string value containing a number.
@@ -772,7 +763,7 @@ func NewBoolean(b bool) *V {
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-func fnLocal(ell *Ell, args []V, result *[]V) bool {
+func fnLocal(ell *Ell, args []V) (result []V, ok bool) {
if len(args) == 0 || args[0].Type != VTypeList {
return ell.Errorf("first argument must be a list")
}
@@ -787,40 +778,38 @@ func fnLocal(ell *Ell, args []V, result *[]V) bool {
values = values[1:]
}
}
- return true
+ return nil, true
}
-func fnSet(ell *Ell, args []V, result *[]V) bool {
+func fnSet(ell *Ell, args []V) (result []V, ok bool) {
if len(args) == 0 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
if len(args) > 1 {
- *result = []V{*args[1].Clone()}
- ell.Set(args[0].String, &(*result)[0])
- return true
+ result = []V{*args[1].Clone()}
+ ell.Set(args[0].String, &result[0])
+ return result, true
}
// We return an empty list for a nil value.
if v := ell.Get(args[0].String); v != nil {
- *result = []V{*v.Clone()}
+ result = []V{*v.Clone()}
} else {
- *result = []V{*NewList(nil)}
+ result = []V{*NewList(nil)}
}
- return true
+ return result, true
}
-func fnList(ell *Ell, args []V, result *[]V) bool {
- *result = []V{*NewList(args)}
- return true
+func fnList(ell *Ell, args []V) (result []V, ok bool) {
+ return []V{*NewList(args)}, true
}
-func fnValues(ell *Ell, args []V, result *[]V) bool {
- *result = args
- return true
+func fnValues(ell *Ell, args []V) (result []V, ok bool) {
+ return args, true
}
-func fnIf(ell *Ell, args []V, result *[]V) bool {
+func fnIf(ell *Ell, args []V) (result []V, ok bool) {
var cond, body, keyword int
for cond = 0; ; cond = keyword + 1 {
if cond >= len(args) {
@@ -831,11 +820,11 @@ func fnIf(ell *Ell, args []V, result *[]V) bool {
}
var res []V
- if !EvalAny(ell, &args[cond], nil, &res) {
- return false
+ if res, ok = EvalAny(ell, &args[cond], nil); !ok {
+ return nil, false
}
if len(res) > 0 && Truthy(&res[0]) {
- return EvalAny(ell, &args[body], nil, result)
+ return EvalAny(ell, &args[body], nil)
}
if keyword = body + 1; keyword >= len(args) {
@@ -850,16 +839,16 @@ func fnIf(ell *Ell, args []V, result *[]V) bool {
if body = keyword + 1; body >= len(args) {
return ell.Errorf("missing body")
}
- return EvalAny(ell, &args[body], nil, result)
+ return EvalAny(ell, &args[body], nil)
case "elif":
default:
return ell.Errorf("invalid keyword: %s", kw)
}
}
- return true
+ return nil, true
}
-func fnMap(ell *Ell, args []V, result *[]V) bool {
+func fnMap(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 {
return ell.Errorf("first argument must be a function")
}
@@ -868,18 +857,17 @@ func fnMap(ell *Ell, args []V, result *[]V) bool {
}
body, values := &args[0], &args[1]
-
- var res []V
for _, v := range values.List {
- if !EvalAny(ell, body, &v, &res) {
- return false
+ res, ok := EvalAny(ell, body, &v)
+ if !ok {
+ return nil, false
}
+ result = append(result, res...)
}
- *result = []V{*NewList(res)}
- return true
+ return []V{*NewList(result)}, true
}
-func fnPrint(ell *Ell, args []V, result *[]V) bool {
+func fnPrint(ell *Ell, args []V) (result []V, ok bool) {
for _, arg := range args {
if arg.Type != VTypeString {
PrintV(os.Stdout, &arg)
@@ -887,10 +875,10 @@ func fnPrint(ell *Ell, args []V, result *[]V) bool {
return ell.Errorf("write failed: %s", err)
}
}
- return true
+ return nil, true
}
-func fnCat(ell *Ell, args []V, result *[]V) bool {
+func fnCat(ell *Ell, args []V) (result []V, ok bool) {
buf := bytes.NewBuffer(nil)
for _, arg := range args {
if arg.Type != VTypeString {
@@ -899,11 +887,10 @@ func fnCat(ell *Ell, args []V, result *[]V) bool {
buf.WriteString(arg.String)
}
}
- *result = []V{*NewString(buf.String())}
- return true
+ return []V{*NewString(buf.String())}, true
}
-func fnSystem(ell *Ell, args []V, result *[]V) bool {
+func fnSystem(ell *Ell, args []V) (result []V, ok bool) {
var argv []string
for _, arg := range args {
if arg.Type != VTypeString {
@@ -922,16 +909,15 @@ func fnSystem(ell *Ell, args []V, result *[]V) bool {
// Approximation of system(3) return value to match C ell at least a bit.
if err := cmd.Run(); err == nil {
- *result = []V{*NewNumber(0)}
+ return []V{*NewNumber(0)}, true
} else if _, ok := err.(*exec.Error); ok {
return ell.Errorf("%s", err)
} else {
- *result = []V{*NewNumber(1)}
+ return []V{*NewNumber(1)}, true
}
- return true
}
-func fnParse(ell *Ell, args []V, result *[]V) bool {
+func fnParse(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
@@ -940,11 +926,10 @@ func fnParse(ell *Ell, args []V, result *[]V) bool {
if err != nil {
return ell.Errorf("%s", err)
}
- *result = []V{*NewList(res)}
- return true
+ return []V{*NewList(res)}, true
}
-func fnTry(ell *Ell, args []V, result *[]V) bool {
+func fnTry(ell *Ell, args []V) (result []V, ok bool) {
var body, handler *V
if len(args) < 1 {
return ell.Errorf("first argument must be a function")
@@ -953,25 +938,23 @@ func fnTry(ell *Ell, args []V, result *[]V) bool {
return ell.Errorf("second argument must be a function")
}
body, handler = &args[0], &args[1]
- if EvalAny(ell, body, nil, result) {
- return true
+ if result, ok = EvalAny(ell, body, nil); ok {
+ return
}
msg := NewString(ell.Error)
ell.Error = ""
- *result = nil
-
- return EvalAny(ell, handler, msg, result)
+ return EvalAny(ell, handler, msg)
}
-func fnThrow(ell *Ell, args []V, result *[]V) bool {
+func fnThrow(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
return ell.Errorf("%s", args[0].String)
}
-func fnPlus(ell *Ell, args []V, result *[]V) bool {
+func fnPlus(ell *Ell, args []V) (result []V, ok bool) {
res := 0.
for _, arg := range args {
if arg.Type != VTypeString {
@@ -983,11 +966,10 @@ func fnPlus(ell *Ell, args []V, result *[]V) bool {
}
res += value
}
- *result = []V{*NewNumber(res)}
- return true
+ return []V{*NewNumber(res)}, true
}
-func fnMinus(ell *Ell, args []V, result *[]V) bool {
+func fnMinus(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
@@ -1010,11 +992,10 @@ func fnMinus(ell *Ell, args []V, result *[]V) bool {
}
res -= value
}
- *result = []V{*NewNumber(res)}
- return true
+ return []V{*NewNumber(res)}, true
}
-func fnMultiply(ell *Ell, args []V, result *[]V) bool {
+func fnMultiply(ell *Ell, args []V) (result []V, ok bool) {
res := 1.
for _, arg := range args {
if arg.Type != VTypeString {
@@ -1026,11 +1007,10 @@ func fnMultiply(ell *Ell, args []V, result *[]V) bool {
}
res *= value
}
- *result = []V{*NewNumber(res)}
- return true
+ return []V{*NewNumber(res)}, true
}
-func fnDivide(ell *Ell, args []V, result *[]V) bool {
+func fnDivide(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
@@ -1049,51 +1029,46 @@ func fnDivide(ell *Ell, args []V, result *[]V) bool {
}
res /= value
}
- *result = []V{*NewNumber(res)}
- return true
+ return []V{*NewNumber(res)}, true
}
-func fnNot(ell *Ell, args []V, result *[]V) bool {
+func fnNot(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 {
return ell.Errorf("missing argument")
}
- *result = []V{*NewBoolean(!Truthy(&args[0]))}
- return true
+ return []V{*NewBoolean(!Truthy(&args[0]))}, true
}
-func fnAnd(ell *Ell, args []V, result *[]V) bool {
+func fnAnd(ell *Ell, args []V) (result []V, ok bool) {
if args == nil {
- *result = []V{*NewBoolean(true)}
- return true
+ return []V{*NewBoolean(true)}, true
}
for _, arg := range args {
- *result = nil
- if !EvalAny(ell, &arg, nil, result) {
- return false
+ result, ok = EvalAny(ell, &arg, nil)
+ if !ok {
+ return nil, false
}
- if len(*result) < 1 || !Truthy(&(*result)[0]) {
- *result = []V{*NewBoolean(false)}
- return true
+ if len(result) < 1 || !Truthy(&result[0]) {
+ return []V{*NewBoolean(false)}, true
}
}
- return true
+ return result, true
}
-func fnOr(ell *Ell, args []V, result *[]V) bool {
+func fnOr(ell *Ell, args []V) (result []V, ok bool) {
for _, arg := range args {
- if !EvalAny(ell, &arg, nil, result) {
- return false
+ result, ok = EvalAny(ell, &arg, nil)
+ if !ok {
+ return nil, false
}
- if len(*result) > 0 && Truthy(&(*result)[0]) {
- return true
+ if len(result) > 0 && Truthy(&result[0]) {
+ return result, true
}
- *result = nil
}
- *result = []V{*NewBoolean(false)}
- return true
+ return []V{*NewBoolean(false)}, true
}
-func fnEq(ell *Ell, args []V, result *[]V) bool {
+func fnEq(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
@@ -1106,11 +1081,10 @@ func fnEq(ell *Ell, args []V, result *[]V) bool {
break
}
}
- *result = []V{*NewBoolean(res)}
- return true
+ return []V{*NewBoolean(res)}, true
}
-func fnLt(ell *Ell, args []V, result *[]V) bool {
+func fnLt(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
@@ -1124,11 +1098,10 @@ func fnLt(ell *Ell, args []V, result *[]V) bool {
}
etalon = arg.String
}
- *result = []V{*NewBoolean(res)}
- return true
+ return []V{*NewBoolean(res)}, true
}
-func fnEquals(ell *Ell, args []V, result *[]V) bool {
+func fnEquals(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
@@ -1149,11 +1122,10 @@ func fnEquals(ell *Ell, args []V, result *[]V) bool {
}
first = second
}
- *result = []V{*NewBoolean(res)}
- return true
+ return []V{*NewBoolean(res)}, true
}
-func fnLess(ell *Ell, args []V, result *[]V) bool {
+func fnLess(ell *Ell, args []V) (result []V, ok bool) {
if len(args) < 1 || args[0].Type != VTypeString {
return ell.Errorf("first argument must be string")
}
@@ -1174,8 +1146,7 @@ func fnLess(ell *Ell, args []V, result *[]V) bool {
}
first = second
}
- *result = []V{*NewBoolean(res)}
- return true
+ return []V{*NewBoolean(res)}, true
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -1233,6 +1204,6 @@ func StdInitialize(ell *Ell) bool {
return false
}
- var result []V
- return ell.EvalBlock(program, nil, &result)
+ _, ok := ell.EvalBlock(program, nil)
+ return ok
}
generated by cgit v1.2.3-70-g09d2 (git 2.47.0) at 2024-11-23 10:12:04 +0000