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// Copyright 2018 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 syntax
import "fmt"
// PosMax is the largest line or column value that can be represented without loss.
// Incoming values (arguments) larger than PosMax will be set to PosMax.
const PosMax = 1 << 30
// A Pos represents an absolute (line, col) source position
// with a reference to position base for computing relative
// (to a file, or line directive) position information.
// Pos values are intentionally light-weight so that they
// can be created without too much concern about space use.
type Pos struct {
base *PosBase
line, col uint32
}
// MakePos returns a new Pos for the given PosBase, line and column.
func MakePos(base *PosBase, line, col uint) Pos { return Pos{base, sat32(line), sat32(col)} }
// TODO(gri) IsKnown makes an assumption about linebase < 1.
// Maybe we should check for Base() != nil instead.
func (pos Pos) Pos() Pos { return pos }
func (pos Pos) IsKnown() bool { return pos.line > 0 }
func (pos Pos) Base() *PosBase { return pos.base }
func (pos Pos) Line() uint { return uint(pos.line) }
func (pos Pos) Col() uint { return uint(pos.col) }
func (pos Pos) RelFilename() string { return pos.base.Filename() }
func (pos Pos) RelLine() uint {
b := pos.base
if b.Line() == 0 {
// base line is unknown => relative line is unknown
return 0
}
return b.Line() + (pos.Line() - b.Pos().Line())
}
func (pos Pos) RelCol() uint {
b := pos.base
if b.Col() == 0 {
// base column is unknown => relative column is unknown
// (the current specification for line directives requires
// this to apply until the next PosBase/line directive,
// not just until the new newline)
return 0
}
if pos.Line() == b.Pos().Line() {
// pos on same line as pos base => column is relative to pos base
return b.Col() + (pos.Col() - b.Pos().Col())
}
return pos.Col()
}
// Cmp compares the positions p and q and returns a result r as follows:
//
// r < 0: p is before q
// r == 0: p and q are the same position (but may not be identical)
// r > 0: p is after q
//
// If p and q are in different files, p is before q if the filename
// of p sorts lexicographically before the filename of q.
func (p Pos) Cmp(q Pos) int {
pname := p.RelFilename()
qname := q.RelFilename()
switch {
case pname < qname:
return -1
case pname > qname:
return +1
}
pline := p.Line()
qline := q.Line()
switch {
case pline < qline:
return -1
case pline > qline:
return +1
}
pcol := p.Col()
qcol := q.Col()
switch {
case pcol < qcol:
return -1
case pcol > qcol:
return +1
}
return 0
}
func (pos Pos) String() string {
rel := position_{pos.RelFilename(), pos.RelLine(), pos.RelCol()}
abs := position_{pos.Base().Pos().RelFilename(), pos.Line(), pos.Col()}
s := rel.String()
if rel != abs {
s += "[" + abs.String() + "]"
}
return s
}
// TODO(gri) cleanup: find better name, avoid conflict with position in error_test.go
type position_ struct {
filename string
line, col uint
}
func (p position_) String() string {
if p.line == 0 {
if p.filename == "" {
return "<unknown position>"
}
return p.filename
}
if p.col == 0 {
return fmt.Sprintf("%s:%d", p.filename, p.line)
}
return fmt.Sprintf("%s:%d:%d", p.filename, p.line, p.col)
}
// A PosBase represents the base for relative position information:
// At position pos, the relative position is filename:line:col.
type PosBase struct {
pos Pos
filename string
line, col uint32
trimmed bool // whether -trimpath has been applied
}
// NewFileBase returns a new PosBase for the given filename.
// A file PosBase's position is relative to itself, with the
// position being filename:1:1.
func NewFileBase(filename string) *PosBase {
return NewTrimmedFileBase(filename, false)
}
// NewTrimmedFileBase is like NewFileBase, but allows specifying Trimmed.
func NewTrimmedFileBase(filename string, trimmed bool) *PosBase {
base := &PosBase{MakePos(nil, linebase, colbase), filename, linebase, colbase, trimmed}
base.pos.base = base
return base
}
// NewLineBase returns a new PosBase for a line directive "line filename:line:col"
// relative to pos, which is the position of the character immediately following
// the comment containing the line directive. For a directive in a line comment,
// that position is the beginning of the next line (i.e., the newline character
// belongs to the line comment).
func NewLineBase(pos Pos, filename string, trimmed bool, line, col uint) *PosBase {
return &PosBase{pos, filename, sat32(line), sat32(col), trimmed}
}
func (base *PosBase) IsFileBase() bool {
if base == nil {
return false
}
return base.pos.base == base
}
func (base *PosBase) Pos() (_ Pos) {
if base == nil {
return
}
return base.pos
}
func (base *PosBase) Filename() string {
if base == nil {
return ""
}
return base.filename
}
func (base *PosBase) Line() uint {
if base == nil {
return 0
}
return uint(base.line)
}
func (base *PosBase) Col() uint {
if base == nil {
return 0
}
return uint(base.col)
}
func (base *PosBase) Trimmed() bool {
if base == nil {
return false
}
return base.trimmed
}
func sat32(x uint) uint32 {
if x > PosMax {
return PosMax
}
return uint32(x)
}
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