// Format formats the given package file originally obtained from src
// and adjusts the result based on the original source via sourceAdj
// and indentAdj.
func Format(
fset *token.FileSet,
file *ast.File,
sourceAdj func(src []byte, indent int) []byte,
indentAdj int,
src []byte,
cfg printer.Config,
) ([]byte, error) {
if sourceAdj == nil {
// Complete source file.
var buf bytes.Buffer
err := cfg.Fprint(&buf, fset, file)
if err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// Partial source file.
// Determine and prepend leading space.
i, j := 0, 0
for j < len(src) && IsSpace(src[j]) {
if src[j] == '\n' {
i = j + 1 // byte offset of last line in leading space
}
j++
}
var res []byte
res = append(res, src[:i]...)
// Determine and prepend indentation of first code line.
// Spaces are ignored unless there are no tabs,
// in which case spaces count as one tab.
indent := 0
hasSpace := false
for _, b := range src[i:j] {
switch b {
case ' ':
hasSpace = true
case '\t':
indent++
}
}
if indent == 0 && hasSpace {
indent = 1
}
for i := 0; i < indent; i++ {
res = append(res, '\t')
}
// Format the source.
// Write it without any leading and trailing space.
cfg.Indent = indent + indentAdj
var buf bytes.Buffer
err := cfg.Fprint(&buf, fset, file)
if err != nil {
return nil, err
}
res = append(res, sourceAdj(buf.Bytes(), cfg.Indent)...)
// Determine and append trailing space.
i = len(src)
for i > 0 && IsSpace(src[i-1]) {
i--
}
return append(res, src[i:]...), nil
}
