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Copy pathmatch.go
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547 lines (495 loc) · 11.9 KB
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package pattern
import (
"fmt"
"go/ast"
"go/token"
"go/types"
"reflect"
)
var tokensByString = map[string]Token{
"INT": Token(token.INT),
"FLOAT": Token(token.FLOAT),
"IMAG": Token(token.IMAG),
"CHAR": Token(token.CHAR),
"STRING": Token(token.STRING),
"+": Token(token.ADD),
"-": Token(token.SUB),
"*": Token(token.MUL),
"/": Token(token.QUO),
"%": Token(token.REM),
"&": Token(token.AND),
"|": Token(token.OR),
"^": Token(token.XOR),
"<<": Token(token.SHL),
">>": Token(token.SHR),
"&^": Token(token.AND_NOT),
"+=": Token(token.ADD_ASSIGN),
"-=": Token(token.SUB_ASSIGN),
"*=": Token(token.MUL_ASSIGN),
"/=": Token(token.QUO_ASSIGN),
"%=": Token(token.REM_ASSIGN),
"&=": Token(token.AND_ASSIGN),
"|=": Token(token.OR_ASSIGN),
"^=": Token(token.XOR_ASSIGN),
"<<=": Token(token.SHL_ASSIGN),
">>=": Token(token.SHR_ASSIGN),
"&^=": Token(token.AND_NOT_ASSIGN),
"&&": Token(token.LAND),
"||": Token(token.LOR),
"<-": Token(token.ARROW),
"++": Token(token.INC),
"--": Token(token.DEC),
"==": Token(token.EQL),
"<": Token(token.LSS),
">": Token(token.GTR),
"=": Token(token.ASSIGN),
"!": Token(token.NOT),
"!=": Token(token.NEQ),
"<=": Token(token.LEQ),
">=": Token(token.GEQ),
":=": Token(token.DEFINE),
"...": Token(token.ELLIPSIS),
"IMPORT": Token(token.IMPORT),
"VAR": Token(token.VAR),
"TYPE": Token(token.TYPE),
"CONST": Token(token.CONST),
"BREAK": Token(token.BREAK),
"CONTINUE": Token(token.CONTINUE),
"GOTO": Token(token.GOTO),
"FALLTHROUGH": Token(token.FALLTHROUGH),
}
func maybeToken(node Node) (Node, bool) {
if node, ok := node.(String); ok {
if tok, ok := tokensByString[string(node)]; ok {
return tok, true
}
return node, false
}
return node, false
}
func isNil(v interface{}) bool {
if v == nil {
return true
}
if _, ok := v.(Nil); ok {
return true
}
return false
}
type matcher interface {
Match(*Matcher, interface{}) (interface{}, bool)
}
type State = map[string]interface{}
type Matcher struct {
TypesInfo *types.Info
State State
}
func (m *Matcher) fork() *Matcher {
state := make(State, len(m.State))
for k, v := range m.State {
state[k] = v
}
return &Matcher{
TypesInfo: m.TypesInfo,
State: state,
}
}
func (m *Matcher) merge(mc *Matcher) {
m.State = mc.State
}
func (m *Matcher) Match(a Node, b ast.Node) bool {
m.State = State{}
_, ok := match(m, a, b)
return ok
}
func Match(a Node, b ast.Node) (*Matcher, bool) {
m := &Matcher{}
ret := m.Match(a, b)
return m, ret
}
// Match two items, which may be (Node, AST) or (AST, AST)
func match(m *Matcher, l, r interface{}) (interface{}, bool) {
if _, ok := r.(Node); ok {
panic("Node mustn't be on right side of match")
}
switch l := l.(type) {
case *ast.ParenExpr:
return match(m, l.X, r)
case *ast.ExprStmt:
return match(m, l.X, r)
case *ast.DeclStmt:
return match(m, l.Decl, r)
case *ast.LabeledStmt:
return match(m, l.Stmt, r)
case *ast.BlockStmt:
return match(m, l.List, r)
case *ast.FieldList:
return match(m, l.List, r)
}
switch r := r.(type) {
case *ast.ParenExpr:
return match(m, l, r.X)
case *ast.ExprStmt:
return match(m, l, r.X)
case *ast.DeclStmt:
return match(m, l, r.Decl)
case *ast.LabeledStmt:
return match(m, l, r.Stmt)
case *ast.BlockStmt:
if r == nil {
return match(m, l, nil)
}
return match(m, l, r.List)
case *ast.FieldList:
if r == nil {
return match(m, l, nil)
}
return match(m, l, r.List)
case *ast.BasicLit:
if r == nil {
return match(m, l, nil)
}
}
if l, ok := l.(matcher); ok {
return l.Match(m, r)
}
if l, ok := l.(Node); ok {
// Matching of pattern with concrete value
return matchNodeAST(m, l, r)
}
if l == nil || r == nil {
return nil, l == r
}
{
ln, ok1 := l.(ast.Node)
rn, ok2 := r.(ast.Node)
if ok1 && ok2 {
return matchAST(m, ln, rn)
}
}
{
obj, ok := l.(types.Object)
if ok {
switch r := r.(type) {
case *ast.Ident:
return obj, obj == m.TypesInfo.ObjectOf(r)
case *ast.SelectorExpr:
return obj, obj == m.TypesInfo.ObjectOf(r.Sel)
default:
return obj, false
}
}
}
{
ln, ok1 := l.([]ast.Expr)
rn, ok2 := r.([]ast.Expr)
if ok1 || ok2 {
if ok1 && !ok2 {
rn = []ast.Expr{r.(ast.Expr)}
} else if !ok1 && ok2 {
ln = []ast.Expr{l.(ast.Expr)}
}
if len(ln) != len(rn) {
return nil, false
}
for i, ll := range ln {
if _, ok := match(m, ll, rn[i]); !ok {
return nil, false
}
}
return r, true
}
}
{
ln, ok1 := l.([]ast.Stmt)
rn, ok2 := r.([]ast.Stmt)
if ok1 || ok2 {
if ok1 && !ok2 {
rn = []ast.Stmt{r.(ast.Stmt)}
} else if !ok1 && ok2 {
ln = []ast.Stmt{l.(ast.Stmt)}
}
if len(ln) != len(rn) {
return nil, false
}
for i, ll := range ln {
if _, ok := match(m, ll, rn[i]); !ok {
return nil, false
}
}
return r, true
}
}
{
ln, ok1 := l.([]*ast.Field)
rn, ok2 := r.([]*ast.Field)
if ok1 || ok2 {
if ok1 && !ok2 {
rn = []*ast.Field{r.(*ast.Field)}
} else if !ok1 && ok2 {
ln = []*ast.Field{l.(*ast.Field)}
}
if len(ln) != len(rn) {
return nil, false
}
for i, ll := range ln {
if _, ok := match(m, ll, rn[i]); !ok {
return nil, false
}
}
return r, true
}
}
panic(fmt.Sprintf("unsupported comparison: %T and %T", l, r))
}
// Match a Node with an AST node
func matchNodeAST(m *Matcher, a Node, b interface{}) (interface{}, bool) {
switch b := b.(type) {
case []ast.Stmt:
// 'a' is not a List or we'd be using its Match
// implementation.
if len(b) != 1 {
return nil, false
}
return match(m, a, b[0])
case []ast.Expr:
// 'a' is not a List or we'd be using its Match
// implementation.
if len(b) != 1 {
return nil, false
}
return match(m, a, b[0])
case ast.Node:
ra := reflect.ValueOf(a)
rb := reflect.ValueOf(b).Elem()
if ra.Type().Name() != rb.Type().Name() {
return nil, false
}
for i := 0; i < ra.NumField(); i++ {
af := ra.Field(i)
fieldName := ra.Type().Field(i).Name
bf := rb.FieldByName(fieldName)
if (bf == reflect.Value{}) {
panic(fmt.Sprintf("internal error: could not find field %s in type %t when comparing with %T", fieldName, b, a))
}
ai := af.Interface()
bi := bf.Interface()
if ai == nil {
return b, bi == nil
}
if _, ok := match(m, ai.(Node), bi); !ok {
return b, false
}
}
return b, true
case nil:
return nil, a == Nil{}
default:
panic(fmt.Sprintf("unhandled type %T", b))
}
}
// Match two AST nodes
func matchAST(m *Matcher, a, b ast.Node) (interface{}, bool) {
ra := reflect.ValueOf(a)
rb := reflect.ValueOf(b)
if ra.Type() != rb.Type() {
return nil, false
}
if ra.IsNil() || rb.IsNil() {
return rb, ra.IsNil() == rb.IsNil()
}
ra = ra.Elem()
rb = rb.Elem()
for i := 0; i < ra.NumField(); i++ {
af := ra.Field(i)
bf := rb.Field(i)
if af.Type() == rtTokPos || af.Type() == rtObject || af.Type() == rtCommentGroup {
continue
}
switch af.Kind() {
case reflect.Slice:
if af.Len() != bf.Len() {
return nil, false
}
for j := 0; j < af.Len(); j++ {
if _, ok := match(m, af.Index(j).Interface().(ast.Node), bf.Index(j).Interface().(ast.Node)); !ok {
return nil, false
}
}
case reflect.String:
if af.String() != bf.String() {
return nil, false
}
case reflect.Int:
if af.Int() != bf.Int() {
return nil, false
}
case reflect.Bool:
if af.Bool() != bf.Bool() {
return nil, false
}
case reflect.Ptr, reflect.Interface:
if _, ok := match(m, af.Interface(), bf.Interface()); !ok {
return nil, false
}
default:
panic(fmt.Sprintf("internal error: unhandled kind %s (%T)", af.Kind(), af.Interface()))
}
}
return b, true
}
func (b Binding) Match(m *Matcher, node interface{}) (interface{}, bool) {
if isNil(b.Node) {
v, ok := m.State[b.Name]
if ok {
// Recall value
return match(m, v, node)
}
// Matching anything
b.Node = Any{}
}
// Store value
if _, ok := m.State[b.Name]; ok {
panic(fmt.Sprintf("binding already created: %s", b.Name))
}
new, ret := match(m, b.Node, node)
if ret {
m.State[b.Name] = new
}
return new, ret
}
func (Any) Match(m *Matcher, node interface{}) (interface{}, bool) {
return node, true
}
func (l List) Match(m *Matcher, node interface{}) (interface{}, bool) {
v := reflect.ValueOf(node)
if v.Kind() == reflect.Slice {
if isNil(l.Head) {
return node, v.Len() == 0
}
if v.Len() == 0 {
return nil, false
}
// OPT(dh): don't check the entire tail if head didn't match
_, ok1 := match(m, l.Head, v.Index(0).Interface())
_, ok2 := match(m, l.Tail, v.Slice(1, v.Len()).Interface())
return node, ok1 && ok2
}
// Our empty list does not equal an untyped Go nil. This way, we can
// tell apart an if with no else and an if with an empty else.
return nil, false
}
func (s String) Match(m *Matcher, node interface{}) (interface{}, bool) {
switch o := node.(type) {
case token.Token:
if tok, ok := maybeToken(s); ok {
return match(m, tok, node)
}
return nil, false
case string:
return o, string(s) == o
default:
return nil, false
}
}
func (tok Token) Match(m *Matcher, node interface{}) (interface{}, bool) {
o, ok := node.(token.Token)
if !ok {
return nil, false
}
return o, token.Token(tok) == o
}
func (Nil) Match(m *Matcher, node interface{}) (interface{}, bool) {
return nil, isNil(node) || reflect.ValueOf(node).IsNil()
}
func (builtin Builtin) Match(m *Matcher, node interface{}) (interface{}, bool) {
r, ok := match(m, Ident(builtin), node)
if !ok {
return nil, false
}
ident := r.(*ast.Ident)
obj := m.TypesInfo.ObjectOf(ident)
if obj != types.Universe.Lookup(ident.Name) {
return nil, false
}
return ident, true
}
func (obj Object) Match(m *Matcher, node interface{}) (interface{}, bool) {
r, ok := match(m, Ident(obj), node)
if !ok {
return nil, false
}
ident := r.(*ast.Ident)
id := m.TypesInfo.ObjectOf(ident)
_, ok = match(m, obj.Name, ident.Name)
return id, ok
}
func (fn Function) Match(m *Matcher, node interface{}) (interface{}, bool) {
var name string
var obj types.Object
r, ok := match(m, Or{Nodes: []Node{Ident{Any{}}, SelectorExpr{Any{}, Any{}}}}, node)
if !ok {
return nil, false
}
switch r := r.(type) {
case *ast.Ident:
obj = m.TypesInfo.ObjectOf(r)
switch obj := obj.(type) {
case *types.Func:
// OPT(dh): optimize this similar to code.FuncName
name = obj.FullName()
case *types.Builtin:
name = obj.Name()
default:
return nil, false
}
case *ast.SelectorExpr:
var ok bool
obj, ok = m.TypesInfo.ObjectOf(r.Sel).(*types.Func)
if !ok {
return nil, false
}
// OPT(dh): optimize this similar to code.FuncName
name = obj.(*types.Func).FullName()
default:
panic("unreachable")
}
_, ok = match(m, fn.Name, name)
return obj, ok
}
func (or Or) Match(m *Matcher, node interface{}) (interface{}, bool) {
for _, opt := range or.Nodes {
mc := m.fork()
if ret, ok := match(mc, opt, node); ok {
m.merge(mc)
return ret, true
}
}
return nil, false
}
func (not Not) Match(m *Matcher, node interface{}) (interface{}, bool) {
_, ok := match(m, not.Node, node)
if ok {
return nil, false
}
return node, true
}
var (
// Types of fields in go/ast structs that we want to skip
rtTokPos = reflect.TypeOf(token.Pos(0))
rtObject = reflect.TypeOf((*ast.Object)(nil))
rtCommentGroup = reflect.TypeOf((*ast.CommentGroup)(nil))
)
var (
_ matcher = Binding{}
_ matcher = Any{}
_ matcher = List{}
_ matcher = String("")
_ matcher = Token(0)
_ matcher = Nil{}
_ matcher = Builtin{}
_ matcher = Object{}
_ matcher = Function{}
_ matcher = Or{}
_ matcher = Not{}
)