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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 oracle
import (
"fmt"
"go/token"
"code.google.com/p/go.tools/go/callgraph"
"code.google.com/p/go.tools/go/ssa"
"code.google.com/p/go.tools/oracle/serial"
)
// Callstack displays an arbitrary path from a root of the callgraph
// to the function at the current position.
//
// The information may be misleading in a context-insensitive
// analysis. e.g. the call path X->Y->Z might be infeasible if Y never
// calls Z when it is called from X. TODO(adonovan): think about UI.
//
// TODO(adonovan): permit user to specify a starting point other than
// the analysis root.
//
func callstack(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return nil, fmt.Errorf("this position is not inside a function")
}
buildSSA(o)
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Run the pointer analysis and build the complete call graph.
o.ptaConfig.BuildCallGraph = true
cg := ptrAnalysis(o).CallGraph
cg.DeleteSyntheticNodes()
// Search for an arbitrary path from a root to the target function.
isEnd := func(n *callgraph.Node) bool { return n.Func == target }
callpath := callgraph.PathSearch(cg.Root, isEnd)
if callpath != nil {
callpath = callpath[1:] // remove synthetic edge from <root>
}
return &callstackResult{
qpos: qpos,
target: target,
callpath: callpath,
}, nil
}
type callstackResult struct {
qpos *QueryPos
target *ssa.Function
callpath []*callgraph.Edge
}
func (r *callstackResult) display(printf printfFunc) {
if r.callpath != nil {
printf(r.qpos, "Found a call path from root to %s", r.target)
printf(r.target, "%s", r.target)
for i := len(r.callpath) - 1; i >= 0; i-- {
edge := r.callpath[i]
printf(edge.Site, "%s from %s", edge.Site.Common().Description(), edge.Caller.Func)
}
} else {
printf(r.target, "%s is unreachable in this analysis scope", r.target)
}
}
func (r *callstackResult) toSerial(res *serial.Result, fset *token.FileSet) {
var callers []serial.Caller
for i := len(r.callpath) - 1; i >= 0; i-- { // (innermost first)
edge := r.callpath[i]
callers = append(callers, serial.Caller{
Pos: fset.Position(edge.Site.Pos()).String(),
Caller: edge.Caller.Func.String(),
Desc: edge.Site.Common().Description(),
})
}
res.Callstack = &serial.CallStack{
Pos: fset.Position(r.target.Pos()).String(),
Target: r.target.String(),
Callers: callers,
}
}
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