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