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// Package file encapsulates the file abstractions used by the ast & parser.
//
package file
import (
"fmt"
"strings"
"gopkg.in/sourcemap.v1"
)
// Idx is a compact encoding of a source position within a file set.
// It can be converted into a Position for a more convenient, but much
// larger, representation.
type Idx int
// Position describes an arbitrary source position
// including the filename, line, and column location.
type Position struct {
Filename string // The filename where the error occurred, if any
Offset int // The src offset
Line int // The line number, starting at 1
Column int // The column number, starting at 1 (The character count)
}
// A Position is valid if the line number is > 0.
func (self *Position) isValid() bool {
return self.Line > 0
}
// String returns a string in one of several forms:
//
// file:line:column A valid position with filename
// line:column A valid position without filename
// file An invalid position with filename
// - An invalid position without filename
//
func (self *Position) String() string {
str := self.Filename
if self.isValid() {
if str != "" {
str += ":"
}
str += fmt.Sprintf("%d:%d", self.Line, self.Column)
}
if str == "" {
str = "-"
}
return str
}
// FileSet
// A FileSet represents a set of source files.
type FileSet struct {
files []*File
last *File
}
// AddFile adds a new file with the given filename and src.
//
// This an internal method, but exported for cross-package use.
func (self *FileSet) AddFile(filename, src string) int {
base := self.nextBase()
file := &File{
name: filename,
src: src,
base: base,
}
self.files = append(self.files, file)
self.last = file
return base
}
func (self *FileSet) nextBase() int {
if self.last == nil {
return 1
}
return self.last.base + len(self.last.src) + 1
}
func (self *FileSet) File(idx Idx) *File {
for _, file := range self.files {
if idx <= Idx(file.base+len(file.src)) {
return file
}
}
return nil
}
// Position converts an Idx in the FileSet into a Position.
func (self *FileSet) Position(idx Idx) *Position {
for _, file := range self.files {
if idx <= Idx(file.base+len(file.src)) {
return file.Position(idx - Idx(file.base))
}
}
return nil
}
type File struct {
name string
src string
base int // This will always be 1 or greater
sm *sourcemap.Consumer
}
func NewFile(filename, src string, base int) *File {
return &File{
name: filename,
src: src,
base: base,
}
}
func (fl *File) WithSourceMap(sm *sourcemap.Consumer) *File {
fl.sm = sm
return fl
}
func (fl *File) Name() string {
return fl.name
}
func (fl *File) Source() string {
return fl.src
}
func (fl *File) Base() int {
return fl.base
}
func (fl *File) Position(idx Idx) *Position {
position := &Position{}
offset := int(idx) - fl.base
if offset >= len(fl.src) || offset < 0 {
return nil
}
src := fl.src[:offset]
position.Filename = fl.name
position.Offset = offset
position.Line = strings.Count(src, "\n") + 1
if index := strings.LastIndex(src, "\n"); index >= 0 {
position.Column = offset - index
} else {
position.Column = len(src) + 1
}
if fl.sm != nil {
if f, _, l, c, ok := fl.sm.Source(position.Line, position.Column); ok {
position.Filename, position.Line, position.Column = f, l, c
}
}
return position
}
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