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// 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 godoc
// ----------------------------------------------------------------------------
// SpotInfo
// A SpotInfo value describes a particular identifier spot in a given file;
// It encodes three values: the SpotKind (declaration or use), a line or
// snippet index "lori", and whether it's a line or index.
//
// The following encoding is used:
//
// bits 32 4 1 0
// value [lori|kind|isIndex]
type SpotInfo uint32
// SpotKind describes whether an identifier is declared (and what kind of
// declaration) or used.
type SpotKind uint32
const (
PackageClause SpotKind = iota
ImportDecl
ConstDecl
TypeDecl
VarDecl
FuncDecl
MethodDecl
Use
nKinds
)
var (
// These must match the SpotKind values above.
name = []string{
"Packages",
"Imports",
"Constants",
"Types",
"Variables",
"Functions",
"Methods",
"Uses",
"Unknown",
}
)
func (x SpotKind) Name() string { return name[x] }
func init() {
// sanity check: if nKinds is too large, the SpotInfo
// accessor functions may need to be updated
if nKinds > 8 {
panic("internal error: nKinds > 8")
}
}
// makeSpotInfo makes a SpotInfo.
func makeSpotInfo(kind SpotKind, lori int, isIndex bool) SpotInfo {
// encode lori: bits [4..32)
x := SpotInfo(lori) << 4
if int(x>>4) != lori {
// lori value doesn't fit - since snippet indices are
// most certainly always smaller then 1<<28, this can
// only happen for line numbers; give it no line number (= 0)
x = 0
}
// encode kind: bits [1..4)
x |= SpotInfo(kind) << 1
// encode isIndex: bit 0
if isIndex {
x |= 1
}
return x
}
func (x SpotInfo) Kind() SpotKind { return SpotKind(x >> 1 & 7) }
func (x SpotInfo) Lori() int { return int(x >> 4) }
func (x SpotInfo) IsIndex() bool { return x&1 != 0 }
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