diff options
Diffstat (limited to 'vendor/golang.org/x/tools/go/ast/astutil/enclosing.go')
| -rw-r--r-- | vendor/golang.org/x/tools/go/ast/astutil/enclosing.go | 627 |
1 files changed, 627 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/go/ast/astutil/enclosing.go b/vendor/golang.org/x/tools/go/ast/astutil/enclosing.go new file mode 100644 index 0000000..6b7052b --- /dev/null +++ b/vendor/golang.org/x/tools/go/ast/astutil/enclosing.go @@ -0,0 +1,627 @@ +// Copyright 2013 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package astutil + +// This file defines utilities for working with source positions. + +import ( + "fmt" + "go/ast" + "go/token" + "sort" +) + +// PathEnclosingInterval returns the node that encloses the source +// interval [start, end), and all its ancestors up to the AST root. +// +// The definition of "enclosing" used by this function considers +// additional whitespace abutting a node to be enclosed by it. +// In this example: +// +// z := x + y // add them +// <-A-> +// <----B-----> +// +// the ast.BinaryExpr(+) node is considered to enclose interval B +// even though its [Pos()..End()) is actually only interval A. +// This behaviour makes user interfaces more tolerant of imperfect +// input. +// +// This function treats tokens as nodes, though they are not included +// in the result. e.g. PathEnclosingInterval("+") returns the +// enclosing ast.BinaryExpr("x + y"). +// +// If start==end, the 1-char interval following start is used instead. +// +// The 'exact' result is true if the interval contains only path[0] +// and perhaps some adjacent whitespace. It is false if the interval +// overlaps multiple children of path[0], or if it contains only +// interior whitespace of path[0]. +// In this example: +// +// z := x + y // add them +// <--C--> <---E--> +// ^ +// D +// +// intervals C, D and E are inexact. C is contained by the +// z-assignment statement, because it spans three of its children (:=, +// x, +). So too is the 1-char interval D, because it contains only +// interior whitespace of the assignment. E is considered interior +// whitespace of the BlockStmt containing the assignment. +// +// Precondition: [start, end) both lie within the same file as root. +// TODO(adonovan): return (nil, false) in this case and remove precond. +// Requires FileSet; see loader.tokenFileContainsPos. +// +// Postcondition: path is never nil; it always contains at least 'root'. +// +func PathEnclosingInterval(root *ast.File, start, end token.Pos) (path []ast.Node, exact bool) { + // fmt.Printf("EnclosingInterval %d %d\n", start, end) // debugging + + // Precondition: node.[Pos..End) and adjoining whitespace contain [start, end). + var visit func(node ast.Node) bool + visit = func(node ast.Node) bool { + path = append(path, node) + + nodePos := node.Pos() + nodeEnd := node.End() + + // fmt.Printf("visit(%T, %d, %d)\n", node, nodePos, nodeEnd) // debugging + + // Intersect [start, end) with interval of node. + if start < nodePos { + start = nodePos + } + if end > nodeEnd { + end = nodeEnd + } + + // Find sole child that contains [start, end). + children := childrenOf(node) + l := len(children) + for i, child := range children { + // [childPos, childEnd) is unaugmented interval of child. + childPos := child.Pos() + childEnd := child.End() + + // [augPos, augEnd) is whitespace-augmented interval of child. + augPos := childPos + augEnd := childEnd + if i > 0 { + augPos = children[i-1].End() // start of preceding whitespace + } + if i < l-1 { + nextChildPos := children[i+1].Pos() + // Does [start, end) lie between child and next child? + if start >= augEnd && end <= nextChildPos { + return false // inexact match + } + augEnd = nextChildPos // end of following whitespace + } + + // fmt.Printf("\tchild %d: [%d..%d)\tcontains interval [%d..%d)?\n", + // i, augPos, augEnd, start, end) // debugging + + // Does augmented child strictly contain [start, end)? + if augPos <= start && end <= augEnd { + _, isToken := child.(tokenNode) + return isToken || visit(child) + } + + // Does [start, end) overlap multiple children? + // i.e. left-augmented child contains start + // but LR-augmented child does not contain end. + if start < childEnd && end > augEnd { + break + } + } + + // No single child contained [start, end), + // so node is the result. Is it exact? + + // (It's tempting to put this condition before the + // child loop, but it gives the wrong result in the + // case where a node (e.g. ExprStmt) and its sole + // child have equal intervals.) + if start == nodePos && end == nodeEnd { + return true // exact match + } + + return false // inexact: overlaps multiple children + } + + if start > end { + start, end = end, start + } + + if start < root.End() && end > root.Pos() { + if start == end { + end = start + 1 // empty interval => interval of size 1 + } + exact = visit(root) + + // Reverse the path: + for i, l := 0, len(path); i < l/2; i++ { + path[i], path[l-1-i] = path[l-1-i], path[i] + } + } else { + // Selection lies within whitespace preceding the + // first (or following the last) declaration in the file. + // The result nonetheless always includes the ast.File. + path = append(path, root) + } + + return +} + +// tokenNode is a dummy implementation of ast.Node for a single token. +// They are used transiently by PathEnclosingInterval but never escape +// this package. +// +type tokenNode struct { + pos token.Pos + end token.Pos +} + +func (n tokenNode) Pos() token.Pos { + return n.pos +} + +func (n tokenNode) End() token.Pos { + return n.end +} + +func tok(pos token.Pos, len int) ast.Node { + return tokenNode{pos, pos + token.Pos(len)} +} + +// childrenOf returns the direct non-nil children of ast.Node n. +// It may include fake ast.Node implementations for bare tokens. +// it is not safe to call (e.g.) ast.Walk on such nodes. +// +func childrenOf(n ast.Node) []ast.Node { + var children []ast.Node + + // First add nodes for all true subtrees. + ast.Inspect(n, func(node ast.Node) bool { + if node == n { // push n + return true // recur + } + if node != nil { // push child + children = append(children, node) + } + return false // no recursion + }) + + // Then add fake Nodes for bare tokens. + switch n := n.(type) { + case *ast.ArrayType: + children = append(children, + tok(n.Lbrack, len("[")), + tok(n.Elt.End(), len("]"))) + + case *ast.AssignStmt: + children = append(children, + tok(n.TokPos, len(n.Tok.String()))) + + case *ast.BasicLit: + children = append(children, + tok(n.ValuePos, len(n.Value))) + + case *ast.BinaryExpr: + children = append(children, tok(n.OpPos, len(n.Op.String()))) + + case *ast.BlockStmt: + children = append(children, + tok(n.Lbrace, len("{")), + tok(n.Rbrace, len("}"))) + + case *ast.BranchStmt: + children = append(children, + tok(n.TokPos, len(n.Tok.String()))) + + case *ast.CallExpr: + children = append(children, + tok(n.Lparen, len("(")), + tok(n.Rparen, len(")"))) + if n.Ellipsis != 0 { + children = append(children, tok(n.Ellipsis, len("..."))) + } + + case *ast.CaseClause: + if n.List == nil { + children = append(children, + tok(n.Case, len("default"))) + } else { + children = append(children, + tok(n.Case, len("case"))) + } + children = append(children, tok(n.Colon, len(":"))) + + case *ast.ChanType: + switch n.Dir { + case ast.RECV: + children = append(children, tok(n.Begin, len("<-chan"))) + case ast.SEND: + children = append(children, tok(n.Begin, len("chan<-"))) + case ast.RECV | ast.SEND: + children = append(children, tok(n.Begin, len("chan"))) + } + + case *ast.CommClause: + if n.Comm == nil { + children = append(children, + tok(n.Case, len("default"))) + } else { + children = append(children, + tok(n.Case, len("case"))) + } + children = append(children, tok(n.Colon, len(":"))) + + case *ast.Comment: + // nop + + case *ast.CommentGroup: + // nop + + case *ast.CompositeLit: + children = append(children, + tok(n.Lbrace, len("{")), + tok(n.Rbrace, len("{"))) + + case *ast.DeclStmt: + // nop + + case *ast.DeferStmt: + children = append(children, + tok(n.Defer, len("defer"))) + + case *ast.Ellipsis: + children = append(children, + tok(n.Ellipsis, len("..."))) + + case *ast.EmptyStmt: + // nop + + case *ast.ExprStmt: + // nop + + case *ast.Field: + // TODO(adonovan): Field.{Doc,Comment,Tag}? + + case *ast.FieldList: + children = append(children, + tok(n.Opening, len("(")), + tok(n.Closing, len(")"))) + + case *ast.File: + // TODO test: Doc + children = append(children, + tok(n.Package, len("package"))) + + case *ast.ForStmt: + children = append(children, + tok(n.For, len("for"))) + + case *ast.FuncDecl: + // TODO(adonovan): FuncDecl.Comment? + + // Uniquely, FuncDecl breaks the invariant that + // preorder traversal yields tokens in lexical order: + // in fact, FuncDecl.Recv precedes FuncDecl.Type.Func. + // + // As a workaround, we inline the case for FuncType + // here and order things correctly. + // + children = nil // discard ast.Walk(FuncDecl) info subtrees + children = append(children, tok(n.Type.Func, len("func"))) + if n.Recv != nil { + children = append(children, n.Recv) + } + children = append(children, n.Name) + if n.Type.Params != nil { + children = append(children, n.Type.Params) + } + if n.Type.Results != nil { + children = append(children, n.Type.Results) + } + if n.Body != nil { + children = append(children, n.Body) + } + + case *ast.FuncLit: + // nop + + case *ast.FuncType: + if n.Func != 0 { + children = append(children, + tok(n.Func, len("func"))) + } + + case *ast.GenDecl: + children = append(children, + tok(n.TokPos, len(n.Tok.String()))) + if n.Lparen != 0 { + children = append(children, + tok(n.Lparen, len("(")), + tok(n.Rparen, len(")"))) + } + + case *ast.GoStmt: + children = append(children, + tok(n.Go, len("go"))) + + case *ast.Ident: + children = append(children, + tok(n.NamePos, len(n.Name))) + + case *ast.IfStmt: + children = append(children, + tok(n.If, len("if"))) + + case *ast.ImportSpec: + // TODO(adonovan): ImportSpec.{Doc,EndPos}? + + case *ast.IncDecStmt: + children = append(children, + tok(n.TokPos, len(n.Tok.String()))) + + case *ast.IndexExpr: + children = append(children, + tok(n.Lbrack, len("{")), + tok(n.Rbrack, len("}"))) + + case *ast.InterfaceType: + children = append(children, + tok(n.Interface, len("interface"))) + + case *ast.KeyValueExpr: + children = append(children, + tok(n.Colon, len(":"))) + + case *ast.LabeledStmt: + children = append(children, + tok(n.Colon, len(":"))) + + case *ast.MapType: + children = append(children, + tok(n.Map, len("map"))) + + case *ast.ParenExpr: + children = append(children, + tok(n.Lparen, len("(")), + tok(n.Rparen, len(")"))) + + case *ast.RangeStmt: + children = append(children, + tok(n.For, len("for")), + tok(n.TokPos, len(n.Tok.String()))) + + case *ast.ReturnStmt: + children = append(children, + tok(n.Return, len("return"))) + + case *ast.SelectStmt: + children = append(children, + tok(n.Select, len("select"))) + + case *ast.SelectorExpr: + // nop + + case *ast.SendStmt: + children = append(children, + tok(n.Arrow, len("<-"))) + + case *ast.SliceExpr: + children = append(children, + tok(n.Lbrack, len("[")), + tok(n.Rbrack, len("]"))) + + case *ast.StarExpr: + children = append(children, tok(n.Star, len("*"))) + + case *ast.StructType: + children = append(children, tok(n.Struct, len("struct"))) + + case *ast.SwitchStmt: + children = append(children, tok(n.Switch, len("switch"))) + + case *ast.TypeAssertExpr: + children = append(children, + tok(n.Lparen-1, len(".")), + tok(n.Lparen, len("(")), + tok(n.Rparen, len(")"))) + + case *ast.TypeSpec: + // TODO(adonovan): TypeSpec.{Doc,Comment}? + + case *ast.TypeSwitchStmt: + children = append(children, tok(n.Switch, len("switch"))) + + case *ast.UnaryExpr: + children = append(children, tok(n.OpPos, len(n.Op.String()))) + + case *ast.ValueSpec: + // TODO(adonovan): ValueSpec.{Doc,Comment}? + + case *ast.BadDecl, *ast.BadExpr, *ast.BadStmt: + // nop + } + + // TODO(adonovan): opt: merge the logic of ast.Inspect() into + // the switch above so we can make interleaved callbacks for + // both Nodes and Tokens in the right order and avoid the need + // to sort. + sort.Sort(byPos(children)) + + return children +} + +type byPos []ast.Node + +func (sl byPos) Len() int { + return len(sl) +} +func (sl byPos) Less(i, j int) bool { + return sl[i].Pos() < sl[j].Pos() +} +func (sl byPos) Swap(i, j int) { + sl[i], sl[j] = sl[j], sl[i] +} + +// NodeDescription returns a description of the concrete type of n suitable +// for a user interface. +// +// TODO(adonovan): in some cases (e.g. Field, FieldList, Ident, +// StarExpr) we could be much more specific given the path to the AST +// root. Perhaps we should do that. +// +func NodeDescription(n ast.Node) string { + switch n := n.(type) { + case *ast.ArrayType: + return "array type" + case *ast.AssignStmt: + return "assignment" + case *ast.BadDecl: + return "bad declaration" + case *ast.BadExpr: + return "bad expression" + case *ast.BadStmt: + return "bad statement" + case *ast.BasicLit: + return "basic literal" + case *ast.BinaryExpr: + return fmt.Sprintf("binary %s operation", n.Op) + case *ast.BlockStmt: + return "block" + case *ast.BranchStmt: + switch n.Tok { + case token.BREAK: + return "break statement" + case token.CONTINUE: + return "continue statement" + case token.GOTO: + return "goto statement" + case token.FALLTHROUGH: + return "fall-through statement" + } + case *ast.CallExpr: + if len(n.Args) == 1 && !n.Ellipsis.IsValid() { + return "function call (or conversion)" + } + return "function call" + case *ast.CaseClause: + return "case clause" + case *ast.ChanType: + return "channel type" + case *ast.CommClause: + return "communication clause" + case *ast.Comment: + return "comment" + case *ast.CommentGroup: + return "comment group" + case *ast.CompositeLit: + return "composite literal" + case *ast.DeclStmt: + return NodeDescription(n.Decl) + " statement" + case *ast.DeferStmt: + return "defer statement" + case *ast.Ellipsis: + return "ellipsis" + case *ast.EmptyStmt: + return "empty statement" + case *ast.ExprStmt: + return "expression statement" + case *ast.Field: + // Can be any of these: + // struct {x, y int} -- struct field(s) + // struct {T} -- anon struct field + // interface {I} -- interface embedding + // interface {f()} -- interface method + // func (A) func(B) C -- receiver, param(s), result(s) + return "field/method/parameter" + case *ast.FieldList: + return "field/method/parameter list" + case *ast.File: + return "source file" + case *ast.ForStmt: + return "for loop" + case *ast.FuncDecl: + return "function declaration" + case *ast.FuncLit: + return "function literal" + case *ast.FuncType: + return "function type" + case *ast.GenDecl: + switch n.Tok { + case token.IMPORT: + return "import declaration" + case token.CONST: + return "constant declaration" + case token.TYPE: + return "type declaration" + case token.VAR: + return "variable declaration" + } + case *ast.GoStmt: + return "go statement" + case *ast.Ident: + return "identifier" + case *ast.IfStmt: + return "if statement" + case *ast.ImportSpec: + return "import specification" + case *ast.IncDecStmt: + if n.Tok == token.INC { + return "increment statement" + } + return "decrement statement" + case *ast.IndexExpr: + return "index expression" + case *ast.InterfaceType: + return "interface type" + case *ast.KeyValueExpr: + return "key/value association" + case *ast.LabeledStmt: + return "statement label" + case *ast.MapType: + return "map type" + case *ast.Package: + return "package" + case *ast.ParenExpr: + return "parenthesized " + NodeDescription(n.X) + case *ast.RangeStmt: + return "range loop" + case *ast.ReturnStmt: + return "return statement" + case *ast.SelectStmt: + return "select statement" + case *ast.SelectorExpr: + return "selector" + case *ast.SendStmt: + return "channel send" + case *ast.SliceExpr: + return "slice expression" + case *ast.StarExpr: + return "*-operation" // load/store expr or pointer type + case *ast.StructType: + return "struct type" + case *ast.SwitchStmt: + return "switch statement" + case *ast.TypeAssertExpr: + return "type assertion" + case *ast.TypeSpec: + return "type specification" + case *ast.TypeSwitchStmt: + return "type switch" + case *ast.UnaryExpr: + return fmt.Sprintf("unary %s operation", n.Op) + case *ast.ValueSpec: + return "value specification" + + } + panic(fmt.Sprintf("unexpected node type: %T", n)) +} |