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revive/rule/early-return.go
Miles Delahunty 4bb48df5d2
refactor: extract shared code for linting if-else chains (#821)
* refactor: extract shared code for linting if-else chains

The rules "early-return", "indent-error-flow" and
"superfluous-else" have a similar structure. This
moves the common logic for classifying if-else chains
to a common package.

A few side benefits:
- "early-return" now handles os.Exit/log.Panicf/etc
- "superfluous-else" now handles (builtin) panic
- "superfluous-else" and "indent-error-flow" now handle if/else
  chains with 2+ "if" branches

* internal/ifelse: style fixes, renames, spelling
2023-05-17 13:51:35 +02:00

47 lines
1.2 KiB
Go

package rule
import (
"fmt"
"github.com/mgechev/revive/internal/ifelse"
"github.com/mgechev/revive/lint"
)
// EarlyReturnRule finds opportunities to reduce nesting by inverting
// the condition of an "if" block.
type EarlyReturnRule struct{}
// Apply applies the rule to given file.
func (e *EarlyReturnRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
return ifelse.Apply(e, file.AST, ifelse.TargetIf)
}
// Name returns the rule name.
func (*EarlyReturnRule) Name() string {
return "early-return"
}
// CheckIfElse evaluates the rule against an ifelse.Chain.
func (e *EarlyReturnRule) CheckIfElse(chain ifelse.Chain) (failMsg string) {
if !chain.Else.Deviates() {
// this rule only applies if the else-block deviates control flow
return
}
if chain.HasPriorNonDeviating && !chain.If.IsEmpty() {
// if we de-indent this block then a previous branch
// might flow into it, affecting program behaviour
return
}
if chain.If.Deviates() {
// avoid overlapping with superfluous-else
return
}
if chain.If.IsEmpty() {
return fmt.Sprintf("if c { } else { %[1]v } can be simplified to if !c { %[1]v }", chain.Else)
}
return fmt.Sprintf("if c { ... } else { %[1]v } can be simplified to if !c { %[1]v } ...", chain.Else)
}