1// Copyright 2013 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package godoc 6 7// ---------------------------------------------------------------------------- 8// SpotInfo 9 10// A SpotInfo value describes a particular identifier spot in a given file; 11// It encodes three values: the SpotKind (declaration or use), a line or 12// snippet index "lori", and whether it's a line or index. 13// 14// The following encoding is used: 15// 16// bits 32 4 1 0 17// value [lori|kind|isIndex] 18// 19type SpotInfo uint32 20 21// SpotKind describes whether an identifier is declared (and what kind of 22// declaration) or used. 23type SpotKind uint32 24 25const ( 26 PackageClause SpotKind = iota 27 ImportDecl 28 ConstDecl 29 TypeDecl 30 VarDecl 31 FuncDecl 32 MethodDecl 33 Use 34 nKinds 35) 36 37var ( 38 // These must match the SpotKind values above. 39 name = []string{ 40 "Packages", 41 "Imports", 42 "Constants", 43 "Types", 44 "Variables", 45 "Functions", 46 "Methods", 47 "Uses", 48 "Unknown", 49 } 50) 51 52func (x SpotKind) Name() string { return name[x] } 53 54func init() { 55 // sanity check: if nKinds is too large, the SpotInfo 56 // accessor functions may need to be updated 57 if nKinds > 8 { 58 panic("internal error: nKinds > 8") 59 } 60} 61 62// makeSpotInfo makes a SpotInfo. 63func makeSpotInfo(kind SpotKind, lori int, isIndex bool) SpotInfo { 64 // encode lori: bits [4..32) 65 x := SpotInfo(lori) << 4 66 if int(x>>4) != lori { 67 // lori value doesn't fit - since snippet indices are 68 // most certainly always smaller then 1<<28, this can 69 // only happen for line numbers; give it no line number (= 0) 70 x = 0 71 } 72 // encode kind: bits [1..4) 73 x |= SpotInfo(kind) << 1 74 // encode isIndex: bit 0 75 if isIndex { 76 x |= 1 77 } 78 return x 79} 80 81func (x SpotInfo) Kind() SpotKind { return SpotKind(x >> 1 & 7) } 82func (x SpotInfo) Lori() int { return int(x >> 4) } 83func (x SpotInfo) IsIndex() bool { return x&1 != 0 } 84