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|
package parser
import (
"bufio"
"bytes"
"encoding/json"
"fmt"
"regexp"
"strings"
"github.com/pkg/errors"
)
const (
keySyntax = "syntax"
keyCheck = "check"
keyEscape = "escape"
)
var validDirectives = map[string]struct{}{
keySyntax: {},
keyEscape: {},
keyCheck: {},
}
type Directive struct {
Name string
Value string
Location []Range
}
// DirectiveParser is a parser for Dockerfile directives that enforces the
// quirks of the directive parser.
type DirectiveParser struct {
line int
regexp *regexp.Regexp
seen map[string]struct{}
done bool
}
func (d *DirectiveParser) setComment(comment string) {
d.regexp = regexp.MustCompile(fmt.Sprintf(`^%s\s*([a-zA-Z][a-zA-Z0-9]*)\s*=\s*(.+?)\s*$`, comment))
}
func (d *DirectiveParser) ParseLine(line []byte) (*Directive, error) {
d.line++
if d.done {
return nil, nil
}
if d.regexp == nil {
d.setComment("#")
}
match := d.regexp.FindSubmatch(line)
if len(match) == 0 {
d.done = true
return nil, nil
}
k := strings.ToLower(string(match[1]))
if _, ok := validDirectives[k]; !ok {
d.done = true
return nil, nil
}
if d.seen == nil {
d.seen = map[string]struct{}{}
}
if _, ok := d.seen[k]; ok {
return nil, errors.Errorf("only one %s parser directive can be used", k)
}
d.seen[k] = struct{}{}
v := string(match[2])
directive := Directive{
Name: k,
Value: v,
Location: []Range{{
Start: Position{Line: d.line},
End: Position{Line: d.line},
}},
}
return &directive, nil
}
func (d *DirectiveParser) ParseAll(data []byte) ([]*Directive, error) {
scanner := bufio.NewScanner(bytes.NewReader(data))
var directives []*Directive
for scanner.Scan() {
if d.done {
break
}
d, err := d.ParseLine(scanner.Bytes())
if err != nil {
return directives, err
}
if d != nil {
directives = append(directives, d)
}
}
return directives, nil
}
// DetectSyntax returns the syntax of provided input.
//
// The traditional dockerfile directives '# syntax = ...' are used by default,
// however, the function will also fallback to c-style directives '// syntax = ...'
// and json-encoded directives '{ "syntax": "..." }'. Finally, starting lines
// with '#!' are treated as shebangs and ignored.
//
// This allows for a flexible range of input formats, and appropriate syntax
// selection.
func DetectSyntax(dt []byte) (string, string, []Range, bool) {
return ParseDirective(keySyntax, dt)
}
func ParseDirective(key string, dt []byte) (string, string, []Range, bool) {
dt, hadShebang, err := discardShebang(dt)
if err != nil {
return "", "", nil, false
}
line := 0
if hadShebang {
line++
}
// use default directive parser, and search for #key=
directiveParser := DirectiveParser{line: line}
if syntax, cmdline, loc, ok := detectDirectiveFromParser(key, dt, directiveParser); ok {
return syntax, cmdline, loc, true
}
// use directive with different comment prefix, and search for //key=
directiveParser = DirectiveParser{line: line}
directiveParser.setComment("//")
if syntax, cmdline, loc, ok := detectDirectiveFromParser(key, dt, directiveParser); ok {
return syntax, cmdline, loc, true
}
// use json directive, and search for { "key": "..." }
jsonDirective := map[string]string{}
if err := json.Unmarshal(dt, &jsonDirective); err == nil {
if v, ok := jsonDirective[key]; ok {
loc := []Range{{
Start: Position{Line: line},
End: Position{Line: line},
}}
return v, v, loc, true
}
}
return "", "", nil, false
}
func detectDirectiveFromParser(key string, dt []byte, parser DirectiveParser) (string, string, []Range, bool) {
directives, _ := parser.ParseAll(dt)
for _, d := range directives {
if d.Name == key {
p, _, _ := strings.Cut(d.Value, " ")
return p, d.Value, d.Location, true
}
}
return "", "", nil, false
}
func discardShebang(dt []byte) ([]byte, bool, error) {
line, rest, _ := bytes.Cut(dt, []byte("\n"))
if bytes.HasPrefix(line, []byte("#!")) {
return rest, true, nil
}
return dt, false, nil
}
|
