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