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|
package whitespace
import (
"go/ast"
"go/token"
)
// Message contains a message
type Message struct {
Pos token.Position
Type MessageType
Message string
}
// MessageType describes what should happen to fix the warning
type MessageType uint8
// List of MessageTypes
const (
MessageTypeLeading MessageType = iota + 1
MessageTypeTrailing
MessageTypeAddAfter
)
// Settings contains settings for edge-cases
type Settings struct {
MultiIf bool
MultiFunc bool
}
// Run runs this linter on the provided code
func Run(file *ast.File, fset *token.FileSet, settings Settings) []Message {
var messages []Message
for _, f := range file.Decls {
decl, ok := f.(*ast.FuncDecl)
if !ok || decl.Body == nil { // decl.Body can be nil for e.g. cgo
continue
}
vis := visitor{file.Comments, fset, nil, make(map[*ast.BlockStmt]bool), settings}
ast.Walk(&vis, decl)
messages = append(messages, vis.messages...)
}
return messages
}
type visitor struct {
comments []*ast.CommentGroup
fset *token.FileSet
messages []Message
wantNewline map[*ast.BlockStmt]bool
settings Settings
}
func (v *visitor) Visit(node ast.Node) ast.Visitor {
if node == nil {
return v
}
if stmt, ok := node.(*ast.IfStmt); ok && v.settings.MultiIf {
checkMultiLine(v, stmt.Body, stmt.Cond)
}
if stmt, ok := node.(*ast.FuncLit); ok && v.settings.MultiFunc {
checkMultiLine(v, stmt.Body, stmt.Type)
}
if stmt, ok := node.(*ast.FuncDecl); ok && v.settings.MultiFunc {
checkMultiLine(v, stmt.Body, stmt.Type)
}
if stmt, ok := node.(*ast.BlockStmt); ok {
wantNewline := v.wantNewline[stmt]
comments := v.comments
if wantNewline {
comments = nil // Comments also count as a newline if we want a newline
}
first, last := firstAndLast(comments, v.fset, stmt.Pos(), stmt.End(), stmt.List)
startMsg := checkStart(v.fset, stmt.Lbrace, first)
if wantNewline && startMsg == nil {
v.messages = append(v.messages, Message{v.fset.Position(stmt.Pos()), MessageTypeAddAfter, `multi-line statement should be followed by a newline`})
} else if !wantNewline && startMsg != nil {
v.messages = append(v.messages, *startMsg)
}
if msg := checkEnd(v.fset, stmt.Rbrace, last); msg != nil {
v.messages = append(v.messages, *msg)
}
}
return v
}
func checkMultiLine(v *visitor, body *ast.BlockStmt, stmtStart ast.Node) {
start, end := posLine(v.fset, stmtStart.Pos()), posLine(v.fset, stmtStart.End())
if end > start { // Check only multi line conditions
v.wantNewline[body] = true
}
}
func posLine(fset *token.FileSet, pos token.Pos) int {
return fset.Position(pos).Line
}
func firstAndLast(comments []*ast.CommentGroup, fset *token.FileSet, start, end token.Pos, stmts []ast.Stmt) (ast.Node, ast.Node) {
if len(stmts) == 0 {
return nil, nil
}
first, last := ast.Node(stmts[0]), ast.Node(stmts[len(stmts)-1])
for _, c := range comments {
if posLine(fset, c.Pos()) == posLine(fset, start) || posLine(fset, c.End()) == posLine(fset, end) {
continue
}
if c.Pos() < start || c.End() > end {
continue
}
if c.Pos() < first.Pos() {
first = c
}
if c.End() > last.End() {
last = c
}
}
return first, last
}
func checkStart(fset *token.FileSet, start token.Pos, first ast.Node) *Message {
if first == nil {
return nil
}
if posLine(fset, start)+1 < posLine(fset, first.Pos()) {
pos := fset.Position(start)
return &Message{pos, MessageTypeLeading, `unnecessary leading newline`}
}
return nil
}
func checkEnd(fset *token.FileSet, end token.Pos, last ast.Node) *Message {
if last == nil {
return nil
}
if posLine(fset, end)-1 > posLine(fset, last.End()) {
pos := fset.Position(end)
return &Message{pos, MessageTypeTrailing, `unnecessary trailing newline`}
}
return nil
}
|
