mirror of
https://github.com/sharkdp/bat
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81 lines
2.1 KiB
Go
81 lines
2.1 KiB
Go
// The hugeparam command identifies by-value parameters that are larger than n bytes.
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//
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// Example:
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// $ ./hugeparams encoding/xml
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package main
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import (
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"flag"
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"fmt"
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"go/ast"
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"go/token"
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"go/types"
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"log"
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"golang.org/x/tools/go/loader"
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)
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//!+
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var bytesFlag = flag.Int("bytes", 48, "maximum parameter size in bytes")
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var sizeof = (&types.StdSizes{8, 8}).Sizeof // the sizeof function
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func PrintHugeParams(fset *token.FileSet, info *types.Info, files []*ast.File) {
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checkTuple := func(descr string, tuple *types.Tuple) {
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for i := 0; i < tuple.Len(); i++ {
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v := tuple.At(i)
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if sz := sizeof(v.Type()); sz > int64(*bytesFlag) {
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fmt.Printf("%s: %q %s: %s = %d bytes\n",
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fset.Position(v.Pos()),
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v.Name(), descr, v.Type(), sz)
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}
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}
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}
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checkSig := func(sig *types.Signature) {
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checkTuple("parameter", sig.Params())
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checkTuple("result", sig.Results())
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}
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for _, file := range files {
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ast.Inspect(file, func(n ast.Node) bool {
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switch n := n.(type) {
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case *ast.FuncDecl:
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checkSig(info.Defs[n.Name].Type().(*types.Signature))
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case *ast.FuncLit:
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checkSig(info.Types[n.Type].Type.(*types.Signature))
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}
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return true
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})
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}
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}
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//!-
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func main() {
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flag.Parse()
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// The loader loads a complete Go program from source code.
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var conf loader.Config
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_, err := conf.FromArgs(flag.Args(), false)
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if err != nil {
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log.Fatal(err) // command syntax error
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}
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lprog, err := conf.Load()
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if err != nil {
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log.Fatal(err) // load error
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}
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for _, info := range lprog.InitialPackages() {
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PrintHugeParams(lprog.Fset, &info.Info, info.Files)
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}
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}
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/*
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//!+output
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% ./hugeparam encoding/xml
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/go/src/encoding/xml/marshal.go:167:50: "start" parameter: encoding/xml.StartElement = 56 bytes
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/go/src/encoding/xml/marshal.go:734:97: "" result: encoding/xml.StartElement = 56 bytes
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/go/src/encoding/xml/marshal.go:761:51: "start" parameter: encoding/xml.StartElement = 56 bytes
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/go/src/encoding/xml/marshal.go:781:68: "start" parameter: encoding/xml.StartElement = 56 bytes
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/go/src/encoding/xml/xml.go:72:30: "" result: encoding/xml.StartElement = 56 bytes
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//!-output
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*/
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