279 lines
6.4 KiB
Go
279 lines
6.4 KiB
Go
package parser
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// line parsers are dispatch calls that parse a single unit of text into a
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// Node object which contains the whole statement. Dockerfiles have varied
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// (but not usually unique, see ONBUILD for a unique example) parsing rules
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// per-command, and these unify the processing in a way that makes it
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// manageable.
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import (
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"encoding/json"
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"errors"
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"fmt"
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"strconv"
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"strings"
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"unicode"
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)
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var (
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errDockerfileJSONNesting = errors.New("You may not nest arrays in Dockerfile statements.")
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)
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// ignore the current argument. This will still leave a command parsed, but
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// will not incorporate the arguments into the ast.
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func parseIgnore(rest string) (*Node, map[string]bool, error) {
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return &Node{}, nil, nil
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}
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// used for onbuild. Could potentially be used for anything that represents a
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// statement with sub-statements.
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//
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// ONBUILD RUN foo bar -> (onbuild (run foo bar))
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//
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func parseSubCommand(rest string) (*Node, map[string]bool, error) {
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_, child, err := parseLine(rest)
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if err != nil {
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return nil, nil, err
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}
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return &Node{Children: []*Node{child}}, nil, nil
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}
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// parse environment like statements. Note that this does *not* handle
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// variable interpolation, which will be handled in the evaluator.
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func parseEnv(rest string) (*Node, map[string]bool, error) {
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// This is kind of tricky because we need to support the old
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// variant: ENV name value
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// as well as the new one: ENV name=value ...
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// The trigger to know which one is being used will be whether we hit
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// a space or = first. space ==> old, "=" ==> new
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const (
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inSpaces = iota // looking for start of a word
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inWord
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inQuote
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)
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words := []string{}
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phase := inSpaces
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word := ""
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quote := '\000'
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blankOK := false
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var ch rune
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for pos := 0; pos <= len(rest); pos++ {
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if pos != len(rest) {
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ch = rune(rest[pos])
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}
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if phase == inSpaces { // Looking for start of word
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if pos == len(rest) { // end of input
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break
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}
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if unicode.IsSpace(ch) { // skip spaces
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continue
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}
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phase = inWord // found it, fall thru
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}
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if (phase == inWord || phase == inQuote) && (pos == len(rest)) {
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if blankOK || len(word) > 0 {
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words = append(words, word)
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}
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break
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}
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if phase == inWord {
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if unicode.IsSpace(ch) {
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phase = inSpaces
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if blankOK || len(word) > 0 {
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words = append(words, word)
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// Look for = and if no there assume
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// we're doing the old stuff and
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// just read the rest of the line
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if !strings.Contains(word, "=") {
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word = strings.TrimSpace(rest[pos:])
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words = append(words, word)
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break
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}
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}
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word = ""
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blankOK = false
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continue
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}
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if ch == '\'' || ch == '"' {
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quote = ch
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blankOK = true
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phase = inQuote
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continue
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}
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if ch == '\\' {
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if pos+1 == len(rest) {
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continue // just skip \ at end
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}
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pos++
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ch = rune(rest[pos])
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}
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word += string(ch)
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continue
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}
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if phase == inQuote {
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if ch == quote {
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phase = inWord
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continue
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}
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if ch == '\\' {
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if pos+1 == len(rest) {
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phase = inWord
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continue // just skip \ at end
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}
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pos++
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ch = rune(rest[pos])
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}
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word += string(ch)
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}
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}
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if len(words) == 0 {
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return nil, nil, fmt.Errorf("ENV must have some arguments")
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}
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// Old format (ENV name value)
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var rootnode *Node
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if !strings.Contains(words[0], "=") {
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node := &Node{}
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rootnode = node
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strs := TOKEN_WHITESPACE.Split(rest, 2)
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if len(strs) < 2 {
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return nil, nil, fmt.Errorf("ENV must have two arguments")
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}
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node.Value = strs[0]
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node.Next = &Node{}
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node.Next.Value = strs[1]
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} else {
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var prevNode *Node
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for i, word := range words {
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if !strings.Contains(word, "=") {
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return nil, nil, fmt.Errorf("Syntax error - can't find = in %q. Must be of the form: name=value", word)
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}
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parts := strings.SplitN(word, "=", 2)
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name := &Node{}
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value := &Node{}
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name.Next = value
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name.Value = parts[0]
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value.Value = parts[1]
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if i == 0 {
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rootnode = name
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} else {
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prevNode.Next = name
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}
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prevNode = value
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}
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}
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return rootnode, nil, nil
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}
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// parses a whitespace-delimited set of arguments. The result is effectively a
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// linked list of string arguments.
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func parseStringsWhitespaceDelimited(rest string) (*Node, map[string]bool, error) {
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node := &Node{}
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rootnode := node
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prevnode := node
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for _, str := range TOKEN_WHITESPACE.Split(rest, -1) { // use regexp
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prevnode = node
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node.Value = str
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node.Next = &Node{}
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node = node.Next
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}
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// XXX to get around regexp.Split *always* providing an empty string at the
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// end due to how our loop is constructed, nil out the last node in the
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// chain.
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prevnode.Next = nil
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return rootnode, nil, nil
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}
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// parsestring just wraps the string in quotes and returns a working node.
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func parseString(rest string) (*Node, map[string]bool, error) {
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n := &Node{}
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n.Value = rest
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return n, nil, nil
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}
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// parseJSON converts JSON arrays to an AST.
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func parseJSON(rest string) (*Node, map[string]bool, error) {
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var (
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myJson []interface{}
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next = &Node{}
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orignext = next
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prevnode = next
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)
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if err := json.Unmarshal([]byte(rest), &myJson); err != nil {
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return nil, nil, err
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}
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for _, str := range myJson {
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switch str.(type) {
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case string:
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case float64:
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str = strconv.FormatFloat(str.(float64), 'G', -1, 64)
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default:
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return nil, nil, errDockerfileJSONNesting
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}
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next.Value = str.(string)
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next.Next = &Node{}
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prevnode = next
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next = next.Next
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}
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prevnode.Next = nil
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return orignext, map[string]bool{"json": true}, nil
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}
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// parseMaybeJSON determines if the argument appears to be a JSON array. If
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// so, passes to parseJSON; if not, quotes the result and returns a single
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// node.
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func parseMaybeJSON(rest string) (*Node, map[string]bool, error) {
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rest = strings.TrimSpace(rest)
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node, attrs, err := parseJSON(rest)
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if err == nil {
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return node, attrs, nil
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}
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if err == errDockerfileJSONNesting {
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return nil, nil, err
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}
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node = &Node{}
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node.Value = rest
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return node, nil, nil
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}
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// parseMaybeJSONToList determines if the argument appears to be a JSON array. If
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// so, passes to parseJSON; if not, attmpts to parse it as a whitespace
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// delimited string.
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func parseMaybeJSONToList(rest string) (*Node, map[string]bool, error) {
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rest = strings.TrimSpace(rest)
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node, attrs, err := parseJSON(rest)
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if err == nil {
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return node, attrs, nil
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}
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if err == errDockerfileJSONNesting {
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return nil, nil, err
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}
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return parseStringsWhitespaceDelimited(rest)
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}
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