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moby--moby/builder/parser/utils.go
Erik Hollensbe 3f2eb353bd builder: provide a friendly message on parser errors
Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
2014-10-15 18:08:23 +00:00

94 lines
2.2 KiB
Go

package parser
import (
"fmt"
"strings"
)
// QuoteString walks characters (after trimming), escapes any quotes and
// escapes, then wraps the whole thing in quotes. Very useful for generating
// argument output in nodes.
func QuoteString(str string) string {
result := ""
chars := strings.Split(strings.TrimSpace(str), "")
for _, char := range chars {
switch char {
case `"`:
result += `\"`
case `\`:
result += `\\`
default:
result += char
}
}
return `"` + result + `"`
}
// dumps the AST defined by `node` as a list of sexps. Returns a string
// suitable for printing.
func (node *Node) Dump() string {
str := ""
str += node.Value
for _, n := range node.Children {
str += "(" + n.Dump() + ")\n"
}
if node.Next != nil {
for n := node.Next; n != nil; n = n.Next {
if len(n.Children) > 0 {
str += " " + n.Dump()
} else {
str += " " + QuoteString(n.Value)
}
}
}
return strings.TrimSpace(str)
}
// performs the dispatch based on the two primal strings, cmd and args. Please
// look at the dispatch table in parser.go to see how these dispatchers work.
func fullDispatch(cmd, args string) (*Node, map[string]bool, error) {
fn := dispatch[cmd]
// Ignore invalid Dockerfile instructions
if fn == nil {
fn = parseIgnore
}
sexp, attrs, err := fn(args)
if err != nil {
return nil, nil, err
}
return sexp, attrs, nil
}
// splitCommand takes a single line of text and parses out the cmd and args,
// which are used for dispatching to more exact parsing functions.
func splitCommand(line string) (string, string, error) {
cmdline := TOKEN_WHITESPACE.Split(line, 2)
if len(cmdline) != 2 {
return "", "", fmt.Errorf("We do not understand this file. Please ensure it is a valid Dockerfile. Parser error at %q", line)
}
cmd := strings.ToLower(cmdline[0])
// the cmd should never have whitespace, but it's possible for the args to
// have trailing whitespace.
return cmd, strings.TrimSpace(cmdline[1]), nil
}
// covers comments and empty lines. Lines should be trimmed before passing to
// this function.
func stripComments(line string) string {
// string is already trimmed at this point
if TOKEN_COMMENT.MatchString(line) {
return TOKEN_COMMENT.ReplaceAllString(line, "")
}
return line
}