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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package span contains support for representing with positions and ranges in
// text files.
package span
import (
"encoding/json"
"fmt"
"path"
)
// Span represents a source code range in standardized form.
type Span struct {
v span
}
// Point represents a single point within a file.
// In general this should only be used as part of a Span, as on its own it
// does not carry enough information.
type Point struct {
v point
}
type span struct {
URI URI `json:"uri"`
Start point `json:"start"`
End point `json:"end"`
}
type point struct {
Line int `json:"line"`
Column int `json:"column"`
Offset int `json:"offset"`
}
// Invalid is a span that reports false from IsValid
var Invalid = Span{v: span{Start: invalidPoint.v, End: invalidPoint.v}}
var invalidPoint = Point{v: point{Line: 0, Column: 0, Offset: -1}}
// Converter is the interface to an object that can convert between line:column
// and offset forms for a single file.
type Converter interface {
//ToPosition converts from an offset to a line:column pair.
ToPosition(offset int) (int, int, error)
//ToOffset converts from a line:column pair to an offset.
ToOffset(line, col int) (int, error)
}
func New(uri URI, start Point, end Point) Span {
s := Span{v: span{URI: uri, Start: start.v, End: end.v}}
s.v.clean()
return s
}
func NewPoint(line, col, offset int) Point {
p := Point{v: point{Line: line, Column: col, Offset: offset}}
p.v.clean()
return p
}
func Compare(a, b Span) int {
if r := CompareURI(a.URI(), b.URI()); r != 0 {
return r
}
if r := comparePoint(a.v.Start, b.v.Start); r != 0 {
return r
}
return comparePoint(a.v.End, b.v.End)
}
func ComparePoint(a, b Point) int {
return comparePoint(a.v, b.v)
}
func comparePoint(a, b point) int {
if !a.hasPosition() {
if a.Offset < b.Offset {
return -1
}
if a.Offset > b.Offset {
return 1
}
return 0
}
if a.Line < b.Line {
return -1
}
if a.Line > b.Line {
return 1
}
if a.Column < b.Column {
return -1
}
if a.Column > b.Column {
return 1
}
return 0
}
func (s Span) HasPosition() bool { return s.v.Start.hasPosition() }
func (s Span) HasOffset() bool { return s.v.Start.hasOffset() }
func (s Span) IsValid() bool { return s.v.Start.isValid() }
func (s Span) IsPoint() bool { return s.v.Start == s.v.End }
func (s Span) URI() URI { return s.v.URI }
func (s Span) Start() Point { return Point{s.v.Start} }
func (s Span) End() Point { return Point{s.v.End} }
func (s *Span) MarshalJSON() ([]byte, error) { return json.Marshal(&s.v) }
func (s *Span) UnmarshalJSON(b []byte) error { return json.Unmarshal(b, &s.v) }
func (p Point) HasPosition() bool { return p.v.hasPosition() }
func (p Point) HasOffset() bool { return p.v.hasOffset() }
func (p Point) IsValid() bool { return p.v.isValid() }
func (p *Point) MarshalJSON() ([]byte, error) { return json.Marshal(&p.v) }
func (p *Point) UnmarshalJSON(b []byte) error { return json.Unmarshal(b, &p.v) }
func (p Point) Line() int {
if !p.v.hasPosition() {
panic(fmt.Errorf("position not set in %v", p.v))
}
return p.v.Line
}
func (p Point) Column() int {
if !p.v.hasPosition() {
panic(fmt.Errorf("position not set in %v", p.v))
}
return p.v.Column
}
func (p Point) Offset() int {
if !p.v.hasOffset() {
panic(fmt.Errorf("offset not set in %v", p.v))
}
return p.v.Offset
}
func (p point) hasPosition() bool { return p.Line > 0 }
func (p point) hasOffset() bool { return p.Offset >= 0 }
func (p point) isValid() bool { return p.hasPosition() || p.hasOffset() }
func (p point) isZero() bool {
return (p.Line == 1 && p.Column == 1) || (!p.hasPosition() && p.Offset == 0)
}
func (s *span) clean() {
//this presumes the points are already clean
if !s.End.isValid() || (s.End == point{}) {
s.End = s.Start
}
}
func (p *point) clean() {
if p.Line < 0 {
p.Line = 0
}
if p.Column <= 0 {
if p.Line > 0 {
p.Column = 1
} else {
p.Column = 0
}
}
if p.Offset == 0 && (p.Line > 1 || p.Column > 1) {
p.Offset = -1
}
}
// Format implements fmt.Formatter to print the Location in a standard form.
// The format produced is one that can be read back in using Parse.
func (s Span) Format(f fmt.State, c rune) {
fullForm := f.Flag('+')
preferOffset := f.Flag('#')
// we should always have a uri, simplify if it is file format
//TODO: make sure the end of the uri is unambiguous
uri := string(s.v.URI)
if c == 'f' {
uri = path.Base(uri)
} else if !fullForm {
uri = s.v.URI.Filename()
}
fmt.Fprint(f, uri)
if !s.IsValid() || (!fullForm && s.v.Start.isZero() && s.v.End.isZero()) {
return
}
// see which bits of start to write
printOffset := s.HasOffset() && (fullForm || preferOffset || !s.HasPosition())
printLine := s.HasPosition() && (fullForm || !printOffset)
printColumn := printLine && (fullForm || (s.v.Start.Column > 1 || s.v.End.Column > 1))
fmt.Fprint(f, ":")
if printLine {
fmt.Fprintf(f, "%d", s.v.Start.Line)
}
if printColumn {
fmt.Fprintf(f, ":%d", s.v.Start.Column)
}
if printOffset {
fmt.Fprintf(f, "#%d", s.v.Start.Offset)
}
// start is written, do we need end?
if s.IsPoint() {
return
}
// we don't print the line if it did not change
printLine = fullForm || (printLine && s.v.End.Line > s.v.Start.Line)
fmt.Fprint(f, "-")
if printLine {
fmt.Fprintf(f, "%d", s.v.End.Line)
}
if printColumn {
if printLine {
fmt.Fprint(f, ":")
}
fmt.Fprintf(f, "%d", s.v.End.Column)
}
if printOffset {
fmt.Fprintf(f, "#%d", s.v.End.Offset)
}
}
func (s Span) WithPosition(c Converter) (Span, error) {
if err := s.update(c, true, false); err != nil {
return Span{}, err
}
return s, nil
}
func (s Span) WithOffset(c Converter) (Span, error) {
if err := s.update(c, false, true); err != nil {
return Span{}, err
}
return s, nil
}
func (s Span) WithAll(c Converter) (Span, error) {
if err := s.update(c, true, true); err != nil {
return Span{}, err
}
return s, nil
}
func (s *Span) update(c Converter, withPos, withOffset bool) error {
if !s.IsValid() {
return fmt.Errorf("cannot add information to an invalid span")
}
if withPos && !s.HasPosition() {
if err := s.v.Start.updatePosition(c); err != nil {
return err
}
if s.v.End.Offset == s.v.Start.Offset {
s.v.End = s.v.Start
} else if err := s.v.End.updatePosition(c); err != nil {
return err
}
}
if withOffset && (!s.HasOffset() || (s.v.End.hasPosition() && !s.v.End.hasOffset())) {
if err := s.v.Start.updateOffset(c); err != nil {
return err
}
if s.v.End.Line == s.v.Start.Line && s.v.End.Column == s.v.Start.Column {
s.v.End.Offset = s.v.Start.Offset
} else if err := s.v.End.updateOffset(c); err != nil {
return err
}
}
return nil
}
func (p *point) updatePosition(c Converter) error {
line, col, err := c.ToPosition(p.Offset)
if err != nil {
return err
}
p.Line = line
p.Column = col
return nil
}
func (p *point) updateOffset(c Converter) error {
offset, err := c.ToOffset(p.Line, p.Column)
if err != nil {
return err
}
p.Offset = offset
return nil
}