456 lines
14 KiB
Go
456 lines
14 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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"reflect"
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)
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type Pattern struct {
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Root Node
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// Relevant contains instances of ast.Node that could potentially
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// initiate a successful match of the pattern.
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Relevant []reflect.Type
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}
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func MustParse(s string) Pattern {
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p := &Parser{AllowTypeInfo: true}
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pat, err := p.Parse(s)
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if err != nil {
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panic(err)
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}
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return pat
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}
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func roots(node Node) []reflect.Type {
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switch node := node.(type) {
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case Or:
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var out []reflect.Type
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for _, el := range node.Nodes {
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out = append(out, roots(el)...)
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}
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return out
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case Not:
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return roots(node.Node)
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case Binding:
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return roots(node.Node)
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case Nil, nil:
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// this branch is reached via bindings
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return allTypes
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default:
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Ts, ok := nodeToASTTypes[reflect.TypeOf(node)]
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if !ok {
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panic(fmt.Sprintf("internal error: unhandled type %T", node))
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}
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return Ts
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}
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}
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var allTypes = []reflect.Type{
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reflect.TypeOf((*ast.RangeStmt)(nil)),
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reflect.TypeOf((*ast.AssignStmt)(nil)),
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reflect.TypeOf((*ast.IndexExpr)(nil)),
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reflect.TypeOf((*ast.Ident)(nil)),
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reflect.TypeOf((*ast.ValueSpec)(nil)),
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reflect.TypeOf((*ast.GenDecl)(nil)),
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reflect.TypeOf((*ast.BinaryExpr)(nil)),
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reflect.TypeOf((*ast.ForStmt)(nil)),
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reflect.TypeOf((*ast.ArrayType)(nil)),
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reflect.TypeOf((*ast.DeferStmt)(nil)),
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reflect.TypeOf((*ast.MapType)(nil)),
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reflect.TypeOf((*ast.ReturnStmt)(nil)),
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reflect.TypeOf((*ast.SliceExpr)(nil)),
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reflect.TypeOf((*ast.StarExpr)(nil)),
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reflect.TypeOf((*ast.UnaryExpr)(nil)),
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reflect.TypeOf((*ast.SendStmt)(nil)),
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reflect.TypeOf((*ast.SelectStmt)(nil)),
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reflect.TypeOf((*ast.ImportSpec)(nil)),
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reflect.TypeOf((*ast.IfStmt)(nil)),
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reflect.TypeOf((*ast.GoStmt)(nil)),
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reflect.TypeOf((*ast.Field)(nil)),
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reflect.TypeOf((*ast.SelectorExpr)(nil)),
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reflect.TypeOf((*ast.StructType)(nil)),
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reflect.TypeOf((*ast.KeyValueExpr)(nil)),
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reflect.TypeOf((*ast.FuncType)(nil)),
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reflect.TypeOf((*ast.FuncLit)(nil)),
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reflect.TypeOf((*ast.FuncDecl)(nil)),
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reflect.TypeOf((*ast.ChanType)(nil)),
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reflect.TypeOf((*ast.CallExpr)(nil)),
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reflect.TypeOf((*ast.CaseClause)(nil)),
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reflect.TypeOf((*ast.CommClause)(nil)),
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reflect.TypeOf((*ast.CompositeLit)(nil)),
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reflect.TypeOf((*ast.EmptyStmt)(nil)),
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reflect.TypeOf((*ast.SwitchStmt)(nil)),
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reflect.TypeOf((*ast.TypeSwitchStmt)(nil)),
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reflect.TypeOf((*ast.TypeAssertExpr)(nil)),
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reflect.TypeOf((*ast.TypeSpec)(nil)),
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reflect.TypeOf((*ast.InterfaceType)(nil)),
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reflect.TypeOf((*ast.BranchStmt)(nil)),
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reflect.TypeOf((*ast.IncDecStmt)(nil)),
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reflect.TypeOf((*ast.BasicLit)(nil)),
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}
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var nodeToASTTypes = map[reflect.Type][]reflect.Type{
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reflect.TypeOf(String("")): nil,
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reflect.TypeOf(Token(0)): nil,
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reflect.TypeOf(List{}): {reflect.TypeOf((*ast.BlockStmt)(nil)), reflect.TypeOf((*ast.FieldList)(nil))},
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reflect.TypeOf(Builtin{}): {reflect.TypeOf((*ast.Ident)(nil))},
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reflect.TypeOf(Object{}): {reflect.TypeOf((*ast.Ident)(nil))},
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reflect.TypeOf(Function{}): {reflect.TypeOf((*ast.Ident)(nil)), reflect.TypeOf((*ast.SelectorExpr)(nil))},
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reflect.TypeOf(Any{}): allTypes,
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reflect.TypeOf(RangeStmt{}): {reflect.TypeOf((*ast.RangeStmt)(nil))},
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reflect.TypeOf(AssignStmt{}): {reflect.TypeOf((*ast.AssignStmt)(nil))},
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reflect.TypeOf(IndexExpr{}): {reflect.TypeOf((*ast.IndexExpr)(nil))},
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reflect.TypeOf(Ident{}): {reflect.TypeOf((*ast.Ident)(nil))},
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reflect.TypeOf(ValueSpec{}): {reflect.TypeOf((*ast.ValueSpec)(nil))},
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reflect.TypeOf(GenDecl{}): {reflect.TypeOf((*ast.GenDecl)(nil))},
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reflect.TypeOf(BinaryExpr{}): {reflect.TypeOf((*ast.BinaryExpr)(nil))},
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reflect.TypeOf(ForStmt{}): {reflect.TypeOf((*ast.ForStmt)(nil))},
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reflect.TypeOf(ArrayType{}): {reflect.TypeOf((*ast.ArrayType)(nil))},
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reflect.TypeOf(DeferStmt{}): {reflect.TypeOf((*ast.DeferStmt)(nil))},
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reflect.TypeOf(MapType{}): {reflect.TypeOf((*ast.MapType)(nil))},
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reflect.TypeOf(ReturnStmt{}): {reflect.TypeOf((*ast.ReturnStmt)(nil))},
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reflect.TypeOf(SliceExpr{}): {reflect.TypeOf((*ast.SliceExpr)(nil))},
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reflect.TypeOf(StarExpr{}): {reflect.TypeOf((*ast.StarExpr)(nil))},
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reflect.TypeOf(UnaryExpr{}): {reflect.TypeOf((*ast.UnaryExpr)(nil))},
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reflect.TypeOf(SendStmt{}): {reflect.TypeOf((*ast.SendStmt)(nil))},
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reflect.TypeOf(SelectStmt{}): {reflect.TypeOf((*ast.SelectStmt)(nil))},
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reflect.TypeOf(ImportSpec{}): {reflect.TypeOf((*ast.ImportSpec)(nil))},
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reflect.TypeOf(IfStmt{}): {reflect.TypeOf((*ast.IfStmt)(nil))},
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reflect.TypeOf(GoStmt{}): {reflect.TypeOf((*ast.GoStmt)(nil))},
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reflect.TypeOf(Field{}): {reflect.TypeOf((*ast.Field)(nil))},
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reflect.TypeOf(SelectorExpr{}): {reflect.TypeOf((*ast.SelectorExpr)(nil))},
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reflect.TypeOf(StructType{}): {reflect.TypeOf((*ast.StructType)(nil))},
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reflect.TypeOf(KeyValueExpr{}): {reflect.TypeOf((*ast.KeyValueExpr)(nil))},
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reflect.TypeOf(FuncType{}): {reflect.TypeOf((*ast.FuncType)(nil))},
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reflect.TypeOf(FuncLit{}): {reflect.TypeOf((*ast.FuncLit)(nil))},
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reflect.TypeOf(FuncDecl{}): {reflect.TypeOf((*ast.FuncDecl)(nil))},
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reflect.TypeOf(ChanType{}): {reflect.TypeOf((*ast.ChanType)(nil))},
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reflect.TypeOf(CallExpr{}): {reflect.TypeOf((*ast.CallExpr)(nil))},
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reflect.TypeOf(CaseClause{}): {reflect.TypeOf((*ast.CaseClause)(nil))},
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reflect.TypeOf(CommClause{}): {reflect.TypeOf((*ast.CommClause)(nil))},
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reflect.TypeOf(CompositeLit{}): {reflect.TypeOf((*ast.CompositeLit)(nil))},
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reflect.TypeOf(EmptyStmt{}): {reflect.TypeOf((*ast.EmptyStmt)(nil))},
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reflect.TypeOf(SwitchStmt{}): {reflect.TypeOf((*ast.SwitchStmt)(nil))},
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reflect.TypeOf(TypeSwitchStmt{}): {reflect.TypeOf((*ast.TypeSwitchStmt)(nil))},
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reflect.TypeOf(TypeAssertExpr{}): {reflect.TypeOf((*ast.TypeAssertExpr)(nil))},
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reflect.TypeOf(TypeSpec{}): {reflect.TypeOf((*ast.TypeSpec)(nil))},
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reflect.TypeOf(InterfaceType{}): {reflect.TypeOf((*ast.InterfaceType)(nil))},
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reflect.TypeOf(BranchStmt{}): {reflect.TypeOf((*ast.BranchStmt)(nil))},
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reflect.TypeOf(IncDecStmt{}): {reflect.TypeOf((*ast.IncDecStmt)(nil))},
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reflect.TypeOf(BasicLit{}): {reflect.TypeOf((*ast.BasicLit)(nil))},
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}
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var requiresTypeInfo = map[string]bool{
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"Function": true,
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"Builtin": true,
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"Object": true,
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}
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type Parser struct {
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// Allow nodes that rely on type information
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AllowTypeInfo bool
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lex *lexer
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cur item
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last *item
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items chan item
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}
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func (p *Parser) Parse(s string) (Pattern, error) {
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p.cur = item{}
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p.last = nil
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p.items = nil
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fset := token.NewFileSet()
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p.lex = &lexer{
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f: fset.AddFile("<input>", -1, len(s)),
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input: s,
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items: make(chan item),
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}
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go p.lex.run()
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p.items = p.lex.items
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root, err := p.node()
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if err != nil {
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// drain lexer if parsing failed
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for range p.lex.items {
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}
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return Pattern{}, err
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}
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if item := <-p.lex.items; item.typ != itemEOF {
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return Pattern{}, fmt.Errorf("unexpected token %s after end of pattern", item.typ)
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}
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return Pattern{
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Root: root,
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Relevant: roots(root),
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}, nil
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}
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func (p *Parser) next() item {
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if p.last != nil {
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n := *p.last
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p.last = nil
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return n
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}
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var ok bool
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p.cur, ok = <-p.items
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if !ok {
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p.cur = item{typ: eof}
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}
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return p.cur
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}
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func (p *Parser) rewind() {
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p.last = &p.cur
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}
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func (p *Parser) peek() item {
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n := p.next()
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p.rewind()
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return n
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}
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func (p *Parser) accept(typ itemType) (item, bool) {
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n := p.next()
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if n.typ == typ {
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return n, true
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}
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p.rewind()
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return item{}, false
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}
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func (p *Parser) unexpectedToken(valid string) error {
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if p.cur.typ == itemError {
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return fmt.Errorf("error lexing input: %s", p.cur.val)
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}
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var got string
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switch p.cur.typ {
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case itemTypeName, itemVariable, itemString:
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got = p.cur.val
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default:
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got = "'" + p.cur.typ.String() + "'"
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}
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pos := p.lex.f.Position(token.Pos(p.cur.pos))
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return fmt.Errorf("%s: expected %s, found %s", pos, valid, got)
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}
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func (p *Parser) node() (Node, error) {
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if _, ok := p.accept(itemLeftParen); !ok {
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return nil, p.unexpectedToken("'('")
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}
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typ, ok := p.accept(itemTypeName)
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if !ok {
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return nil, p.unexpectedToken("Node type")
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}
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var objs []Node
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for {
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if _, ok := p.accept(itemRightParen); ok {
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break
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} else {
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p.rewind()
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obj, err := p.object()
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if err != nil {
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return nil, err
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}
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objs = append(objs, obj)
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}
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}
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return p.populateNode(typ.val, objs)
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}
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func populateNode(typ string, objs []Node, allowTypeInfo bool) (Node, error) {
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T, ok := structNodes[typ]
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if !ok {
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return nil, fmt.Errorf("unknown node %s", typ)
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}
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if !allowTypeInfo && requiresTypeInfo[typ] {
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return nil, fmt.Errorf("Node %s requires type information", typ)
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}
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pv := reflect.New(T)
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v := pv.Elem()
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if v.NumField() == 1 {
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f := v.Field(0)
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if f.Type().Kind() == reflect.Slice {
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// Variadic node
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f.Set(reflect.AppendSlice(f, reflect.ValueOf(objs)))
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return v.Interface().(Node), nil
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}
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}
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if len(objs) != v.NumField() {
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return nil, fmt.Errorf("tried to initialize node %s with %d values, expected %d", typ, len(objs), v.NumField())
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}
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for i := 0; i < v.NumField(); i++ {
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f := v.Field(i)
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if f.Kind() == reflect.String {
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if obj, ok := objs[i].(String); ok {
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f.Set(reflect.ValueOf(string(obj)))
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} else {
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return nil, fmt.Errorf("first argument of (Binding name node) must be string, but got %s", objs[i])
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}
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} else {
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f.Set(reflect.ValueOf(objs[i]))
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}
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}
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return v.Interface().(Node), nil
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}
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func (p *Parser) populateNode(typ string, objs []Node) (Node, error) {
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return populateNode(typ, objs, p.AllowTypeInfo)
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}
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var structNodes = map[string]reflect.Type{
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"Any": reflect.TypeOf(Any{}),
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"Ellipsis": reflect.TypeOf(Ellipsis{}),
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"List": reflect.TypeOf(List{}),
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"Binding": reflect.TypeOf(Binding{}),
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"RangeStmt": reflect.TypeOf(RangeStmt{}),
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"AssignStmt": reflect.TypeOf(AssignStmt{}),
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"IndexExpr": reflect.TypeOf(IndexExpr{}),
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"Ident": reflect.TypeOf(Ident{}),
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"Builtin": reflect.TypeOf(Builtin{}),
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"ValueSpec": reflect.TypeOf(ValueSpec{}),
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"GenDecl": reflect.TypeOf(GenDecl{}),
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"BinaryExpr": reflect.TypeOf(BinaryExpr{}),
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"ForStmt": reflect.TypeOf(ForStmt{}),
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"ArrayType": reflect.TypeOf(ArrayType{}),
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"DeferStmt": reflect.TypeOf(DeferStmt{}),
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"MapType": reflect.TypeOf(MapType{}),
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"ReturnStmt": reflect.TypeOf(ReturnStmt{}),
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"SliceExpr": reflect.TypeOf(SliceExpr{}),
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"StarExpr": reflect.TypeOf(StarExpr{}),
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"UnaryExpr": reflect.TypeOf(UnaryExpr{}),
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"SendStmt": reflect.TypeOf(SendStmt{}),
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"SelectStmt": reflect.TypeOf(SelectStmt{}),
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"ImportSpec": reflect.TypeOf(ImportSpec{}),
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"IfStmt": reflect.TypeOf(IfStmt{}),
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"GoStmt": reflect.TypeOf(GoStmt{}),
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"Field": reflect.TypeOf(Field{}),
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"SelectorExpr": reflect.TypeOf(SelectorExpr{}),
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"StructType": reflect.TypeOf(StructType{}),
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"KeyValueExpr": reflect.TypeOf(KeyValueExpr{}),
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"FuncType": reflect.TypeOf(FuncType{}),
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"FuncLit": reflect.TypeOf(FuncLit{}),
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"FuncDecl": reflect.TypeOf(FuncDecl{}),
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"ChanType": reflect.TypeOf(ChanType{}),
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"CallExpr": reflect.TypeOf(CallExpr{}),
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"CaseClause": reflect.TypeOf(CaseClause{}),
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"CommClause": reflect.TypeOf(CommClause{}),
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"CompositeLit": reflect.TypeOf(CompositeLit{}),
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"EmptyStmt": reflect.TypeOf(EmptyStmt{}),
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"SwitchStmt": reflect.TypeOf(SwitchStmt{}),
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"TypeSwitchStmt": reflect.TypeOf(TypeSwitchStmt{}),
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"TypeAssertExpr": reflect.TypeOf(TypeAssertExpr{}),
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"TypeSpec": reflect.TypeOf(TypeSpec{}),
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"InterfaceType": reflect.TypeOf(InterfaceType{}),
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"BranchStmt": reflect.TypeOf(BranchStmt{}),
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"IncDecStmt": reflect.TypeOf(IncDecStmt{}),
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"BasicLit": reflect.TypeOf(BasicLit{}),
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"Object": reflect.TypeOf(Object{}),
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"Function": reflect.TypeOf(Function{}),
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"Or": reflect.TypeOf(Or{}),
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"Not": reflect.TypeOf(Not{}),
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}
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func (p *Parser) object() (Node, error) {
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n := p.next()
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switch n.typ {
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case itemLeftParen:
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p.rewind()
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node, err := p.node()
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if err != nil {
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return node, err
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}
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if p.peek().typ == itemColon {
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p.next()
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tail, err := p.object()
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if err != nil {
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return node, err
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}
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return List{Head: node, Tail: tail}, nil
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}
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return node, nil
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case itemLeftBracket:
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p.rewind()
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return p.array()
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case itemVariable:
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v := n
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if v.val == "nil" {
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return Nil{}, nil
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}
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var b Binding
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if _, ok := p.accept(itemAt); ok {
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o, err := p.node()
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if err != nil {
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return nil, err
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}
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b = Binding{
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Name: v.val,
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Node: o,
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}
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} else {
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p.rewind()
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b = Binding{Name: v.val}
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}
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if p.peek().typ == itemColon {
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p.next()
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tail, err := p.object()
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if err != nil {
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return b, err
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}
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return List{Head: b, Tail: tail}, nil
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}
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return b, nil
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case itemBlank:
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return Any{}, nil
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case itemString:
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return String(n.val), nil
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default:
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return nil, p.unexpectedToken("object")
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}
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}
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func (p *Parser) array() (Node, error) {
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if _, ok := p.accept(itemLeftBracket); !ok {
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return nil, p.unexpectedToken("'['")
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}
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var objs []Node
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for {
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if _, ok := p.accept(itemRightBracket); ok {
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break
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} else {
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p.rewind()
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obj, err := p.object()
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if err != nil {
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return nil, err
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}
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objs = append(objs, obj)
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}
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}
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tail := List{}
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for i := len(objs) - 1; i >= 0; i-- {
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l := List{
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Head: objs[i],
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Tail: tail,
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}
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tail = l
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}
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return tail, nil
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}
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/*
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Node ::= itemLeftParen itemTypeName Object* itemRightParen
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Object ::= Node | Array | Binding | itemVariable | itemBlank | itemString
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Array := itemLeftBracket Object* itemRightBracket
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Array := Object itemColon Object
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Binding ::= itemVariable itemAt Node
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*/
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