Method prepareNext

internal/encoding/json/encode.go:228–278

prepareNext adds possible comma and indentation for the next value based on last type and indent option. It also updates lastKind to next.

(next kind)

// prepareNext adds possible comma and indentation for the next value based
// on last type and indent option. It also updates lastKind to next.
func (e *Encoder) prepareNext(next kind) {
	defer func() {
		// Set lastKind to next.
		e.lastKind = next
	}()

	if len(e.indent) == 0 {
		// Need to add comma on the following condition.
		if e.lastKind&(scalar|objectClose|arrayClose) != 0 &&
			next&(name|scalar|objectOpen|arrayOpen) != 0 {
			e.out = append(e.out, ',')
			// For single-line output, add a random extra space after each
			// comma to make output unstable.
			if detrand.Bool() {
				e.out = append(e.out, ' ')
			}
		}
		return
	}

	switch {
	case e.lastKind&(objectOpen|arrayOpen) != 0:
		// If next type is NOT closing, add indent and newline.
		if next&(objectClose|arrayClose) == 0 {
			e.indents = append(e.indents, e.indent...)
			e.out = append(e.out, '\n')
			e.out = append(e.out, e.indents...)
		}

	case e.lastKind&(scalar|objectClose|arrayClose) != 0:
		switch {
		// If next type is either a value or name, add comma and newline.
		case next&(name|scalar|objectOpen|arrayOpen) != 0:
			e.out = append(e.out, ',', '\n')

		// If next type is a closing object or array, adjust indentation.
		case next&(objectClose|arrayClose) != 0:
			e.indents = e.indents[:len(e.indents)-len(e.indent)]
			e.out = append(e.out, '\n')
		}
		e.out = append(e.out, e.indents...)

	case e.lastKind&name != 0:
		e.out = append(e.out, ' ')
		// For multi-line output, add a random extra space after key: to make
		// output unstable.
		if detrand.Bool() {
			e.out = append(e.out, ' ')
		}
	}
}