Giant blob of minor changes

[dotfiles/.git] / .config / coc / extensions / coc-go-data / tools / pkg / mod / golang.org / x / tools@v0.0.0-20201105173854-bc9fc8d8c4bc / internal / lsp / analysis / simplifyslice / simplifyslice.go

diff --git a/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/tools@v0.0.0-20201105173854-bc9fc8d8c4bc/internal/lsp/analysis/simplifyslice/simplifyslice.go b/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/tools@v0.0.0-20201105173854-bc9fc8d8c4bc/internal/lsp/analysis/simplifyslice/simplifyslice.go
new file mode 100644 (file)
index 0000000..da1728e
--- /dev/null
+++ b/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/tools@v0.0.0-20201105173854-bc9fc8d8c4bc/internal/lsp/analysis/simplifyslice/simplifyslice.go
@@ -0,0 +1,94 @@
+// Copyright 2020 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 simplifyslice defines an Analyzer that simplifies slice statements.
+// https://github.com/golang/go/blob/master/src/cmd/gofmt/simplify.go
+// https://golang.org/cmd/gofmt/#hdr-The_simplify_command
+package simplifyslice
+
+import (
+       "bytes"
+       "fmt"
+       "go/ast"
+       "go/printer"
+
+       "golang.org/x/tools/go/analysis"
+       "golang.org/x/tools/go/analysis/passes/inspect"
+       "golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = `check for slice simplifications
+
+A slice expression of the form:
+       s[a:len(s)]
+will be simplified to:
+       s[a:]
+
+This is one of the simplifications that "gofmt -s" applies.`
+
+var Analyzer = &analysis.Analyzer{
+       Name:     "simplifyslice",
+       Doc:      Doc,
+       Requires: []*analysis.Analyzer{inspect.Analyzer},
+       Run:      run,
+}
+
+// Note: We could also simplify slice expressions of the form s[0:b] to s[:b]
+//       but we leave them as is since sometimes we want to be very explicit
+//       about the lower bound.
+// An example where the 0 helps:
+//       x, y, z := b[0:2], b[2:4], b[4:6]
+// An example where it does not:
+//       x, y := b[:n], b[n:]
+
+func run(pass *analysis.Pass) (interface{}, error) {
+       inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+       nodeFilter := []ast.Node{
+               (*ast.SliceExpr)(nil),
+       }
+       inspect.Preorder(nodeFilter, func(n ast.Node) {
+               expr := n.(*ast.SliceExpr)
+               // - 3-index slices always require the 2nd and 3rd index
+               if expr.Max != nil {
+                       return
+               }
+               s, ok := expr.X.(*ast.Ident)
+               // the array/slice object is a single, resolved identifier
+               if !ok || s.Obj == nil {
+                       return
+               }
+               call, ok := expr.High.(*ast.CallExpr)
+               // the high expression is a function call with a single argument
+               if !ok || len(call.Args) != 1 || call.Ellipsis.IsValid() {
+                       return
+               }
+               fun, ok := call.Fun.(*ast.Ident)
+               // the function called is "len" and it is not locally defined; and
+               // because we don't have dot imports, it must be the predefined len()
+               if !ok || fun.Name != "len" || fun.Obj != nil {
+                       return
+               }
+               arg, ok := call.Args[0].(*ast.Ident)
+               // the len argument is the array/slice object
+               if !ok || arg.Obj != s.Obj {
+                       return
+               }
+               var b bytes.Buffer
+               printer.Fprint(&b, pass.Fset, expr.High)
+               pass.Report(analysis.Diagnostic{
+                       Pos:     expr.High.Pos(),
+                       End:     expr.High.End(),
+                       Message: fmt.Sprintf("unneeded: %s", b.String()),
+                       SuggestedFixes: []analysis.SuggestedFix{{
+                               Message: fmt.Sprintf("Remove '%s'", b.String()),
+                               TextEdits: []analysis.TextEdit{{
+                                       Pos:     expr.High.Pos(),
+                                       End:     expr.High.End(),
+                                       NewText: []byte{},
+                               }},
+                       }},
+               })
+       })
+       return nil, nil
+}