83 lines
1.6 KiB
Go
83 lines
1.6 KiB
Go
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package rule
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import (
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"fmt"
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"go/ast"
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"strings"
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"github.com/mgechev/revive/lint"
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)
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// RangeRule lints given else constructs.
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type RangeRule struct{}
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// Apply applies the rule to given file.
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func (r *RangeRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
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var failures []lint.Failure
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onFailure := func(failure lint.Failure) {
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failures = append(failures, failure)
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}
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w := &lintRanges{file, onFailure}
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ast.Walk(w, file.AST)
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return failures
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}
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// Name returns the rule name.
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func (r *RangeRule) Name() string {
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return "range"
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}
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type lintRanges struct {
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file *lint.File
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onFailure func(lint.Failure)
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}
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func (w *lintRanges) Visit(node ast.Node) ast.Visitor {
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rs, ok := node.(*ast.RangeStmt)
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if !ok {
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return w
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}
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if rs.Value == nil {
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// for x = range m { ... }
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return w // single var form
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}
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if !isIdent(rs.Value, "_") {
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// for ?, y = range m { ... }
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return w
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}
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newRS := *rs // shallow copy
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newRS.Value = nil
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w.onFailure(lint.Failure{
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Failure: fmt.Sprintf("should omit 2nd value from range; this loop is equivalent to `for %s %s range ...`", w.file.Render(rs.Key), rs.Tok),
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Confidence: 1,
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Node: rs.Value,
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ReplacementLine: firstLineOf(w.file, &newRS, rs),
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})
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return w
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}
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func firstLineOf(f *lint.File, node, match ast.Node) string {
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line := f.Render(node)
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if i := strings.Index(line, "\n"); i >= 0 {
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line = line[:i]
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}
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return indentOf(f, match) + line
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}
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func indentOf(f *lint.File, node ast.Node) string {
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line := srcLine(f.Content(), f.ToPosition(node.Pos()))
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for i, r := range line {
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switch r {
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case ' ', '\t':
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default:
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return line[:i]
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}
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}
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return line // unusual or empty line
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}
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