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1257 lines (1106 loc) · 26.9 KB
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package main
import (
"bytes"
"fmt"
"io"
"math"
"os"
"sort"
"strconv"
"strings"
"sync"
)
// byte slice helpers from the Ink interpreter source code,
// github.com/thesephist/ink
// zero-extend a slice of bytes to given length
func zeroExtend(s []byte, max int) []byte {
if max <= len(s) {
return s
}
extended := make([]byte, max)
copy(extended, s)
return extended
}
// return the max length of two slices
func maxLen(a, b []byte) int {
if alen, blen := len(a), len(b); alen < blen {
return blen
} else {
return alen
}
}
type Value interface {
String() string
Eq(Value) bool
}
type EmptyValue byte
// interned "empty" value
const empty EmptyValue = 0
func (v EmptyValue) String() string {
return "_"
}
func (v EmptyValue) Eq(u Value) bool {
return true
}
// Null need not contain any data, so we use the most compact data
// representation we can.
type NullValue byte
// interned "null"
const null NullValue = 0
func (v NullValue) String() string {
return "?"
}
func (v NullValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if _, ok := u.(NullValue); ok {
return true
}
return false
}
type StringValue []byte
func MakeString(s string) *StringValue {
v := StringValue(s)
return &v
}
func (v *StringValue) String() string {
return fmt.Sprintf("'%s'", string(*v))
}
func (v *StringValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if w, ok := u.(*StringValue); ok {
return bytes.Equal(*v, *w)
}
return false
}
func (v *StringValue) stringContent() string {
return string(*v)
}
type IntValue int64
func (v IntValue) String() string {
return strconv.FormatInt(int64(v), 10)
}
func (v IntValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if w, ok := u.(IntValue); ok {
return v == w
} else if w, ok := u.(FloatValue); ok {
return FloatValue(v) == w
}
return false
}
type FloatValue float64
func (v FloatValue) String() string {
return strconv.FormatFloat(float64(v), 'g', -1, 64)
}
func (v FloatValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if w, ok := u.(FloatValue); ok {
return v == w
} else if w, ok := u.(IntValue); ok {
return v == FloatValue(w)
}
return false
}
type BoolValue bool
// interned bools
const oakTrue = BoolValue(true)
const oakFalse = BoolValue(false)
func (v BoolValue) String() string {
if v {
return "true"
}
return "false"
}
func (v BoolValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if w, ok := u.(BoolValue); ok {
return v == w
}
return false
}
type AtomValue string
func (v AtomValue) String() string {
return ":" + string(v)
}
func (v AtomValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if w, ok := u.(AtomValue); ok {
return v == w
}
return false
}
type ListValue []Value
func MakeList(xs ...Value) *ListValue {
v := ListValue(xs)
return &v
}
func (v *ListValue) String() string {
valStrings := make([]string, len(*v))
for i, val := range *v {
valStrings[i] = val.String()
}
return "[" + strings.Join(valStrings, ", ") + "]"
}
func (v *ListValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if w, ok := u.(*ListValue); ok {
if len(*v) != len(*w) {
return false
}
for i, el := range *v {
if !el.Eq((*w)[i]) {
return false
}
}
return true
}
return false
}
type ObjectValue map[string]Value
// only used for efficient serialization to string
type serializedObjEntry struct {
key string
full string
}
func (v ObjectValue) String() string {
// TODO: fix how this deals with circular references
entries := make([]serializedObjEntry, len(v))
i := 0
for key, val := range v {
entries[i] = serializedObjEntry{
key: key,
full: key + ": " + val.String(),
}
i++
}
// sort entries lexicographically for easier debugging use
sort.Slice(entries, func(i, j int) bool {
return entries[i].key < entries[j].key
})
sb := strings.Builder{}
sb.WriteString("{")
for i, entry := range entries {
if i != 0 {
sb.WriteString(", ")
}
sb.WriteString(entry.full)
}
sb.WriteString("}")
return sb.String()
}
func (v ObjectValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if w, ok := u.(ObjectValue); ok {
if len(v) != len(w) {
return false
}
for key, val := range v {
if wVal, ok := w[key]; ok {
if !val.Eq(wVal) {
return false
}
} else {
return false
}
}
return true
}
return false
}
type FnValue struct {
defn *fnNode
scope
}
func (v FnValue) String() string {
return v.defn.String()
}
func (v FnValue) Eq(u Value) bool {
if _, ok := u.(EmptyValue); ok {
return true
}
if w, ok := u.(FnValue); ok {
return v.defn == w.defn
}
return false
}
type thunkValue struct {
defn *fnNode
scope
}
func (v thunkValue) String() string {
return fmt.Sprintf("thunk of fn %s: %s", v.defn.name, v.defn.body)
}
func (v thunkValue) Eq(u Value) bool {
panic("Illegal to compare thunk values!")
}
func (c *Context) unwrapThunk(thunk thunkValue) (v Value, err *runtimeError) {
for isThunk := true; isThunk; thunk, isThunk = v.(thunkValue) {
v, err = c.evalExprWithOpt(thunk.defn.body, thunk.scope, true)
if err != nil {
err.stackTrace = append(err.stackTrace, stackEntry{
name: thunk.defn.name,
pos: thunk.defn.pos(),
})
return
}
}
return
}
type scope struct {
parent *scope
vars map[string]Value
}
func (sc *scope) get(name string) (Value, *runtimeError) {
if v, ok := sc.vars[name]; ok {
return v, nil
}
if sc.parent != nil {
return sc.parent.get(name)
}
return nil, &runtimeError{
reason: fmt.Sprintf("%s is undefined", name),
}
}
func (sc *scope) put(name string, v Value) {
sc.vars[name] = v
}
func (sc *scope) update(name string, v Value) *runtimeError {
if _, ok := sc.vars[name]; ok {
sc.vars[name] = v
return nil
}
if sc.parent != nil {
return sc.parent.update(name, v)
}
return &runtimeError{
reason: fmt.Sprintf("%s is undefined", name),
}
}
type engine struct {
// interpreter lock to ensure lack of data races
sync.Mutex
// interpreter event loop waitgroup
sync.WaitGroup
// for deduplicating imports
importMap map[string]scope
// file fd -> Go's File map
fileMap map[uintptr]*os.File
fdLock sync.Mutex
// log async error streams through this
reportErr func(error)
}
type Context struct {
// shared interpreter state
eng *engine
// directory containing the root file of this context, used for loading
// other modules with relative paths / URLs
rootPath string
// top level ("global") scope of this context
scope
}
func NewContext(rootPath string) Context {
eng := engine{
importMap: map[string]scope{},
fileMap: map[uintptr]*os.File{},
reportErr: func(err error) {
fmt.Println(err)
},
}
return Context{
eng: &eng,
rootPath: rootPath,
scope: scope{
parent: nil,
vars: map[string]Value{},
},
}
}
func NewContextWithCwd() Context {
cwd, err := os.Getwd()
if err != nil {
fmt.Println("Could not get working directory")
os.Exit(1)
}
return NewContext(cwd)
}
func (c *Context) ChildContext(rootPath string) Context {
return Context{
eng: c.eng,
rootPath: rootPath,
scope: scope{
parent: nil,
vars: map[string]Value{},
},
}
}
func (c *Context) subScope(parent *scope) {
c.scope = scope{
parent: parent,
vars: map[string]Value{},
}
}
func (c *Context) Lock() {
c.eng.Lock()
}
func (c *Context) Unlock() {
c.eng.Unlock()
}
func (c *Context) Wait() {
c.eng.Wait()
}
type stackEntry struct {
name string
pos
}
func (e stackEntry) String() string {
if e.name != "" {
return fmt.Sprintf(" in fn %s %s", e.name, e.pos)
}
return fmt.Sprintf(" in anonymous fn %s", e.pos)
}
type runtimeError struct {
reason string
pos
stackTrace []stackEntry
}
func (e *runtimeError) Error() string {
trace := make([]string, len(e.stackTrace))
for i, entry := range e.stackTrace {
trace[i] = entry.String()
}
return fmt.Sprintf("Runtime error %s: %s\n%s", e.pos, e.reason, strings.Join(trace, "\n"))
}
func (c *Context) Eval(programReader io.Reader) (Value, error) {
c.Lock()
defer c.Unlock()
program, err := io.ReadAll(programReader)
if err != nil {
return nil, err
}
tokenizer := newTokenizer(string(program))
tokens := tokenizer.tokenize()
parser := newParser(tokens)
nodes, err := parser.parse()
if err != nil {
return nil, err
}
val, runtimeErr := c.evalNodes(nodes)
if runtimeErr == nil {
return val, nil
}
return val, runtimeErr
}
func (c *Context) EvalFnValue(maybeFn Value, thunkable bool, args ...Value) (Value, *runtimeError) {
if fn, ok := maybeFn.(FnValue); ok {
// if not enough arguments, fill them with nulls
difference := len(fn.defn.args) - len(args)
for i := 0; i < difference; i++ {
args = append(args, null)
}
fnScope := scope{
parent: &fn.scope,
vars: map[string]Value{},
}
for i, argName := range fn.defn.args {
if argName != "" {
fnScope.put(argName, args[i])
}
}
if fn.defn.restArg != "" {
var restList ListValue
if len(args) > len(fn.defn.args) {
restList = ListValue(args[len(fn.defn.args):])
} else {
restList = ListValue{}
}
fnScope.put(fn.defn.restArg, &restList)
}
thunk := thunkValue{
defn: fn.defn,
scope: fnScope,
}
if thunkable {
return thunk, nil
}
return c.unwrapThunk(thunk)
} else if fn, ok := maybeFn.(BuiltinFnValue); ok {
return fn.fn(args)
}
return nil, &runtimeError{
reason: fmt.Sprintf("%s is not a function and cannot be called", maybeFn),
}
}
func (c *Context) evalNodes(nodes []astNode) (Value, *runtimeError) {
var returnVal Value = null
var err *runtimeError
for _, expr := range nodes {
returnVal, err = c.evalExpr(expr, c.scope)
if err != nil {
return nil, err
}
}
return returnVal, nil
}
var divisionByZeroErr = runtimeError{
reason: fmt.Sprintf("Division by zero"),
}
func intBinaryOp(op tokKind, left, right IntValue) (Value, *runtimeError) {
switch op {
case plus:
return IntValue(left + right), nil
case minus:
return IntValue(left - right), nil
case times:
return IntValue(left * right), nil
case divide:
if right == 0 {
return nil, &divisionByZeroErr
}
return FloatValue(FloatValue(left) / FloatValue(right)), nil
case modulus:
if right == 0 {
return nil, &divisionByZeroErr
}
return IntValue(left % right), nil
case xor:
return IntValue(left ^ right), nil
case and:
return IntValue(left & right), nil
case or:
return IntValue(left | right), nil
case greater:
return BoolValue(left > right), nil
case less:
return BoolValue(left < right), nil
case geq:
return BoolValue(left >= right), nil
case leq:
return BoolValue(left <= right), nil
}
return nil, &runtimeError{
reason: fmt.Sprintf("Invalid binary operator %s for ints %s, %s", token{kind: op}, left, right),
}
}
func floatBinaryOp(op tokKind, left, right FloatValue) (Value, *runtimeError) {
switch op {
case plus:
return FloatValue(left + right), nil
case minus:
return FloatValue(left - right), nil
case times:
return FloatValue(left * right), nil
case divide:
if right == 0 {
return nil, &divisionByZeroErr
}
return FloatValue(left / right), nil
case modulus:
if right == 0 {
return nil, &divisionByZeroErr
}
return FloatValue(math.Mod(float64(left), float64(right))), nil
case greater:
return BoolValue(left > right), nil
case less:
return BoolValue(left < right), nil
case geq:
return BoolValue(left >= right), nil
case leq:
return BoolValue(left <= right), nil
}
return nil, &runtimeError{
reason: fmt.Sprintf("Invalid binary operator %s for floats %s, %s", token{kind: op}, left, right),
}
}
func (c *Context) evalAsObjKey(node astNode, sc scope) (Value, *runtimeError) {
if ident, ok := node.(identifierNode); ok {
return MakeString(ident.payload), nil
}
return c.evalExpr(node, sc)
}
func (c *Context) evalExpr(node astNode, sc scope) (Value, *runtimeError) {
return c.evalExprWithOpt(node, sc, false)
}
func incompatibleError(op tokKind, left, right Value, position pos) *runtimeError {
return &runtimeError{
reason: fmt.Sprintf("Cannot %s incompatible values %s, %s",
token{kind: op}, left, right),
pos: position,
}
}
func (c *Context) evalExprWithOpt(node astNode, sc scope, thunkable bool) (Value, *runtimeError) {
switch n := node.(type) {
case emptyNode:
return empty, nil
case nullNode:
return null, nil
case stringNode:
payload := make([]byte, len(n.payload), len(n.payload))
copy(payload, n.payload)
v := StringValue(payload)
return &v, nil
case intNode:
return IntValue(n.payload), nil
case floatNode:
return FloatValue(n.payload), nil
case boolNode:
return BoolValue(n.payload), nil
case atomNode:
return AtomValue(n.payload), nil
case listNode:
var err *runtimeError
elems := make([]Value, len(n.elems))
for i, elNode := range n.elems {
elems[i], err = c.evalExpr(elNode, sc)
if err != nil {
return nil, err
}
}
list := ListValue(elems)
return &list, nil
case objectNode:
obj := ObjectValue{}
for _, entry := range n.entries {
var keyString string
if identKey, ok := entry.key.(identifierNode); ok {
keyString = identKey.payload
} else {
key, err := c.evalExpr(entry.key, sc)
if err != nil {
return nil, err
}
switch typedKey := key.(type) {
case *StringValue:
keyString = string(*typedKey)
case AtomValue:
keyString = string(typedKey)
case IntValue:
keyString = typedKey.String()
case FloatValue:
keyString = typedKey.String()
default:
return nil, &runtimeError{reason: fmt.Sprintf("Expected a string, atom, or number as object key, got %s", key.String()),
pos: entry.key.pos(),
}
}
}
val, err := c.evalExpr(entry.val, sc)
if err != nil {
return nil, err
}
obj[keyString] = val
}
return obj, nil
case fnNode:
fn := FnValue{
defn: &n,
scope: sc,
}
if fn.defn.name != "" {
sc.put(fn.defn.name, fn)
}
return fn, nil
case identifierNode:
val, err := sc.get(n.payload)
if err != nil {
err.pos = n.pos()
}
return val, err
case assignmentNode:
assignedValue, err := c.evalExpr(n.right, sc)
if err != nil {
return nil, err
}
switch left := n.left.(type) {
case identifierNode:
if n.isLocal {
sc.put(left.payload, assignedValue)
} else {
err := sc.update(left.payload, assignedValue)
if err != nil {
err.pos = n.pos()
return nil, err
}
}
return assignedValue, nil
case listNode:
assignedList, ok := assignedValue.(*ListValue)
if !ok {
return nil, &runtimeError{
reason: fmt.Sprintf("right side %s of list destructuring is not a list", n.right),
pos: n.pos(),
}
}
for i, mustBeIdent := range left.elems {
ident, ok := mustBeIdent.(identifierNode)
if !ok {
if _, ok = mustBeIdent.(emptyNode); ok {
continue
}
return nil, &runtimeError{
reason: fmt.Sprintf("element %s in destructured list %s is not an identifier", mustBeIdent, left),
pos: n.pos(),
}
}
var destructuredEl Value
if i < len(*assignedList) {
destructuredEl = (*assignedList)[i]
} else {
destructuredEl = null
}
if n.isLocal {
sc.put(ident.payload, destructuredEl)
} else {
err := sc.update(ident.payload, destructuredEl)
if err != nil {
return nil, err
}
}
}
return assignedValue, nil
case objectNode:
assignedObj, ok := assignedValue.(ObjectValue)
if !ok {
return nil, &runtimeError{
reason: fmt.Sprintf("right side %s of object destructuring is not an object", n.right),
pos: n.pos(),
}
}
for _, entryNode := range left.entries {
key, err := c.evalAsObjKey(entryNode.key, sc)
if err != nil {
return nil, err
}
mustBeIdent := entryNode.val
ident, ok := mustBeIdent.(identifierNode)
if !ok {
if _, ok = mustBeIdent.(emptyNode); ok {
continue
}
return nil, &runtimeError{
reason: fmt.Sprintf("value %s in destructured object %s is not an identifier", mustBeIdent, left),
pos: n.pos(),
}
}
var keyString string
if k, ok := key.(*StringValue); ok {
keyString = string(*k)
} else if k, ok := key.(AtomValue); ok {
keyString = string(k)
} else {
keyString = key.String()
}
var destructuredEl Value
if val, ok := assignedObj[keyString]; ok {
destructuredEl = val
} else {
destructuredEl = null
}
if n.isLocal {
sc.put(ident.payload, destructuredEl)
} else {
err := sc.update(ident.payload, destructuredEl)
if err != nil {
return nil, err
}
}
}
return assignedValue, nil
case propertyAccessNode:
assign := left
assignLeft, err := c.evalExpr(assign.left, sc)
if err != nil {
return nil, err
}
assignRight, err := c.evalAsObjKey(assign.right, sc)
if err != nil {
return nil, err
}
switch target := assignLeft.(type) {
case *StringValue:
assignedString, ok := assignedValue.(*StringValue)
if !ok {
return nil, &runtimeError{
reason: fmt.Sprintf("Cannot assign non-string value %s to string in %s", assignedValue, assign),
pos: n.pos(),
}
}
byteIndexVal, ok := assignRight.(IntValue)
if !ok {
return nil, &runtimeError{
reason: fmt.Sprintf("Cannot index into string with non-integer index %s", assignRight),
pos: n.pos(),
}
}
byteIndex := int(byteIndexVal)
if byteIndex < 0 || byteIndex > len(*target) {
return nil, &runtimeError{
reason: fmt.Sprintf("String assignment index %d out of range in %s", byteIndex, n),
pos: n.pos(),
}
}
if byteIndex == len(*target) {
// append
*target = append(*target, *assignedString...)
} else {
for byteOffset, byteAtOffset := range *assignedString {
if byteIndex+byteOffset < len(*target) {
(*target)[byteIndex+byteOffset] = byteAtOffset
} else {
*target = append(*target, byteAtOffset)
}
}
}
case *ListValue:
listIndexVal, ok := assignRight.(IntValue)
if !ok {
return nil, &runtimeError{
reason: fmt.Sprintf("Cannot index into list with non-integer index %s", assignRight),
pos: n.pos(),
}
}
listIndex := int(listIndexVal)
if listIndex < 0 || listIndex > len(*target) {
return nil, &runtimeError{
reason: fmt.Sprintf("List assignment index %d out of range in %s", listIndex, n),
pos: n.pos(),
}
}
if listIndex == len(*target) {
*target = append(*target, assignedValue)
} else {
(*target)[listIndex] = assignedValue
}
case ObjectValue:
var objKeyString string
if objKey, ok := assignRight.(*StringValue); ok {
objKeyString = string(*objKey)
} else if objKey, ok := assignRight.(AtomValue); ok {
objKeyString = string(objKey)
} else {
objKeyString = assignRight.String()
}
if _, ok := assignedValue.(EmptyValue); ok {
delete(target, objKeyString)
} else {
target[objKeyString] = assignedValue
}
default:
return nil, &runtimeError{
reason: fmt.Sprintf("Expected string, list, or object in left-hand side of property assignment, got %s", left.String()),
pos: n.pos(),
}
}
return assignLeft, nil
default:
return nil, &runtimeError{
reason: fmt.Sprintf("Invalid assignment target %s", left.String()),
pos: n.pos(),
}
}
case propertyAccessNode:
left, err := c.evalExpr(n.left, sc)
if err != nil {
return nil, err
}
right, err := c.evalAsObjKey(n.right, sc)
if err != nil {
return nil, err
}
switch target := left.(type) {
case *StringValue:
byteIndex, ok := right.(IntValue)
if !ok {
return nil, &runtimeError{
reason: fmt.Sprintf("Cannot index into string with non-integer index %s", right),
pos: n.pos(),
}
}
if byteIndex < 0 || int64(byteIndex) >= int64(len(*target)) {
return null, nil
}
targetByte := StringValue([]byte{(*target)[byteIndex]})
return &targetByte, nil
case *ListValue:
listIndex, ok := right.(IntValue)
if !ok {
return nil, &runtimeError{
reason: fmt.Sprintf("Cannot index into list with non-integer index %s", right),
pos: n.pos(),
}
}
if listIndex < 0 || int64(listIndex) >= int64(len(*target)) {
return null, nil
}
return (*target)[listIndex], nil
case ObjectValue:
var objKeyString string
if objKey, ok := right.(*StringValue); ok {
objKeyString = string(*objKey)
} else if objKey, ok := right.(AtomValue); ok {
objKeyString = string(objKey)
} else {
objKeyString = right.String()
}
if val, ok := target[objKeyString]; ok {
return val, nil
}
return null, nil
}
return nil, &runtimeError{
reason: fmt.Sprintf("Expected string, list, or object in left-hand side of property access, got %s", left.String()),
pos: n.pos(),
}
case unaryNode:
rightComputed, err := c.evalExpr(n.right, sc)
if err != nil {
return nil, err