delve/service/api/prettyprint.go

package api

import (
	"bytes"
	"fmt"
	"reflect"
)

const (
	// strings longer than this will cause slices, arrays and structs to be printed on multiple lines when newlines is enabled
	maxShortStringLen = 7
	// string used for one indentation level (when printing on multiple lines)
	indentString = "\t"
)

// Returns a representation of v on a single line
func (v *Variable) SinglelineString() string {
	var buf bytes.Buffer
	v.writeTo(&buf, true, false, true, "")
	return buf.String()
}

// Returns a representation of v on multiple lines
func (v *Variable) MultilineString(indent string) string {
	var buf bytes.Buffer
	buf.WriteString(indent)
	v.writeTo(&buf, true, true, true, indent)
	return buf.String()
}

func (v *Variable) writeTo(buf *bytes.Buffer, top, newlines, includeType bool, indent string) {
	if v.Unreadable != "" {
		fmt.Fprintf(buf, "(unreadable %s)", v.Unreadable)
		return
	}

	if !top && v.Addr == 0 {
		fmt.Fprintf(buf, "%s nil", v.Type)
		return
	}

	switch v.Kind {
	case reflect.Slice:
		v.writeSliceTo(buf, newlines, includeType, indent)
	case reflect.Array:
		v.writeArrayTo(buf, newlines, includeType, indent)
	case reflect.Ptr:
		if v.Type == "" {
			fmt.Fprintf(buf, "nil")
		} else if v.Children[0].OnlyAddr {
			fmt.Fprintf(buf, "(%s)(0x%x)", v.Type, v.Children[0].Addr)
		} else {
			fmt.Fprintf(buf, "*")
			v.Children[0].writeTo(buf, false, newlines, includeType, indent)
		}
	case reflect.UnsafePointer:
		fmt.Fprintf(buf, "unsafe.Pointer(0x%x)", v.Children[0].Addr)
	case reflect.String:
		v.writeStringTo(buf)
	case reflect.Chan:
		if newlines {
			v.writeStructTo(buf, newlines, includeType, indent)
		} else {
			if len(v.Children) == 0 {
				fmt.Fprintf(buf, "%s nil", v.Type)
			} else {
				fmt.Fprintf(buf, "%s %s/%s", v.Type, v.Children[0].Value, v.Children[1].Value)
			}
		}
	case reflect.Struct:
		v.writeStructTo(buf, newlines, includeType, indent)
	case reflect.Interface:
		if includeType {
			if v.Children[0].Kind == reflect.Invalid {
				fmt.Fprintf(buf, "%s ", v.Type)
				if v.Children[0].Addr == 0 {
					fmt.Fprintf(buf, "nil")
					return
				}
			} else {
				fmt.Fprintf(buf, "%s(%s) ", v.Type, v.Children[0].Type)
			}
		}
		v.Children[0].writeTo(buf, false, newlines, false, indent)
	case reflect.Map:
		v.writeMapTo(buf, newlines, includeType, indent)
	case reflect.Func:
		if v.Value == "" {
			fmt.Fprintf(buf, "nil")
		} else {
			fmt.Fprintf(buf, "%s", v.Value)
		}
	case reflect.Complex64, reflect.Complex128:
		fmt.Fprintf(buf, "(%s + %si)", v.Children[0].Value, v.Children[1].Value)
	default:
		if v.Value != "" {
			buf.Write([]byte(v.Value))
		} else {
			fmt.Fprintf(buf, "(unknown %s)", v.Kind)
		}
	}
}

func (v *Variable) writeStringTo(buf *bytes.Buffer) {
	s := v.Value
	if len(s) != int(v.Len) {
		s = fmt.Sprintf("%s...+%d more", s, int(v.Len)-len(s))
	}
	fmt.Fprintf(buf, "%q", s)
}

func (v *Variable) writeSliceTo(buf *bytes.Buffer, newlines, includeType bool, indent string) {
	if includeType {
		fmt.Fprintf(buf, "%s len: %d, cap: %d, ", v.Type, v.Len, v.Cap)
	}
	v.writeSliceOrArrayTo(buf, newlines, indent)
}

func (v *Variable) writeArrayTo(buf *bytes.Buffer, newlines, includeType bool, indent string) {
	if includeType {
		fmt.Fprintf(buf, "%s ", v.Type)
	}
	v.writeSliceOrArrayTo(buf, newlines, indent)
}

func (v *Variable) writeStructTo(buf *bytes.Buffer, newlines, includeType bool, indent string) {
	if int(v.Len) != len(v.Children) {
		fmt.Fprintf(buf, "(*%s)(0x%x)", v.Type, v.Addr)
		return
	}

	if includeType {
		fmt.Fprintf(buf, "%s ", v.Type)
	}

	nl := v.shouldNewlineStruct(newlines)

	fmt.Fprintf(buf, "{")

	for i := range v.Children {
		if nl {
			fmt.Fprintf(buf, "\n%s%s", indent, indentString)
		}
		fmt.Fprintf(buf, "%s: ", v.Children[i].Name)
		v.Children[i].writeTo(buf, false, nl, true, indent+indentString)
		if i != len(v.Children)-1 || nl {
			fmt.Fprintf(buf, ",")
			if !nl {
				fmt.Fprintf(buf, " ")
			}
		}
	}

	if nl {
		fmt.Fprintf(buf, "\n%s", indent)
	}
	fmt.Fprintf(buf, "}")
}

func (v *Variable) writeMapTo(buf *bytes.Buffer, newlines, includeType bool, indent string) {
	if includeType {
		fmt.Fprintf(buf, "%s ", v.Type)
	}

	nl := newlines && (len(v.Children) > 0)

	fmt.Fprintf(buf, "[")

	for i := 0; i < len(v.Children); i += 2 {
		key := &v.Children[i]
		value := &v.Children[i+1]

		if nl {
			fmt.Fprintf(buf, "\n%s%s", indent, indentString)
		}

		key.writeTo(buf, false, false, false, indent+indentString)
		fmt.Fprintf(buf, ": ")
		value.writeTo(buf, false, nl, false, indent+indentString)
		if i != len(v.Children)-1 || nl {
			fmt.Fprintf(buf, ", ")
		}
	}

	if len(v.Children)/2 != int(v.Len) {
		if nl {
			fmt.Fprintf(buf, "\n%s%s", indent, indentString)
		} else {
			fmt.Fprintf(buf, ",")
		}
		fmt.Fprintf(buf, "...+%d more", int(v.Len)-(len(v.Children)/2))
	}

	if nl {
		fmt.Fprintf(buf, "\n%s", indent)
	}
	fmt.Fprintf(buf, "]")
}

func (v *Variable) shouldNewlineArray(newlines bool) bool {
	if !newlines || len(v.Children) == 0 {
		return false
	}

	kind, hasptr := (&v.Children[0]).recursiveKind()

	switch kind {
	case reflect.Slice, reflect.Array, reflect.Struct, reflect.Map, reflect.Interface:
		return true
	case reflect.String:
		if hasptr {
			return true
		}
		for i := range v.Children {
			if len(v.Children[i].Value) > maxShortStringLen {
				return true
			}
		}
		return false
	default:
		return false
	}
}

func (v *Variable) recursiveKind() (reflect.Kind, bool) {
	hasptr := false
	var kind reflect.Kind
	for {
		kind = v.Kind
		if kind == reflect.Ptr {
			hasptr = true
			v = &(v.Children[0])
		} else {
			break
		}
	}
	return kind, hasptr
}

func (v *Variable) shouldNewlineStruct(newlines bool) bool {
	if !newlines || len(v.Children) == 0 {
		return false
	}

	for i := range v.Children {
		kind, hasptr := (&v.Children[i]).recursiveKind()

		switch kind {
		case reflect.Slice, reflect.Array, reflect.Struct, reflect.Map, reflect.Interface:
			return true
		case reflect.String:
			if hasptr {
				return true
			}
			if len(v.Children[i].Value) > maxShortStringLen {
				return true
			}
		}
	}

	return false
}

func (v *Variable) writeSliceOrArrayTo(buf *bytes.Buffer, newlines bool, indent string) {
	nl := v.shouldNewlineArray(newlines)
	fmt.Fprintf(buf, "[")

	for i := range v.Children {
		if nl {
			fmt.Fprintf(buf, "\n%s%s", indent, indentString)
		}
		v.Children[i].writeTo(buf, false, nl, false, indent+indentString)
		if i != len(v.Children)-1 || nl {
			fmt.Fprintf(buf, ",")
		}
	}

	if len(v.Children) != int(v.Len) {
		if nl {
			fmt.Fprintf(buf, "\n%s%s", indent, indentString)
		} else {
			fmt.Fprintf(buf, ",")
		}
		fmt.Fprintf(buf, "...+%d more", int(v.Len)-len(v.Children))
	}

	if nl {
		fmt.Fprintf(buf, "\n%s", indent)
	}

	fmt.Fprintf(buf, "]")
}