parser

Documentation

Overview

This package implements a parser and parse tree dumper for Dockerfiles.

Index

• Variables
• func QuoteString(str string) string
• type Node
  • func Parse(rwc io.Reader) (*Node, error)
  • func (node *Node) Dump() string

Variables

var (
	TOKEN_WHITESPACE        = regexp.MustCompile(`[\t\v\f\r ]+`)
	TOKEN_LINE_CONTINUATION = regexp.MustCompile(`\\\s*$`)
	TOKEN_COMMENT           = regexp.MustCompile(`^#.*$`)
)

Functions

func QuoteString

func QuoteString(str string) string

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.

Types

type Node

type Node struct {
	Value      string          // actual content
	Next       *Node           // the next item in the current sexp
	Children   []*Node         // the children of this sexp
	Attributes map[string]bool // special attributes for this node
	Original   string          // original line used before parsing
}

Node is a structure used to represent a parse tree.

In the node there are three fields, Value, Next, and Children. Value is the current token's string value. Next is always the next non-child token, and children contains all the children. Here's an example:

(value next (child child-next child-next-next) next-next)

This data structure is frankly pretty lousy for handling complex languages, but lucky for us the Dockerfile isn't very complicated. This structure works a little more effectively than a "proper" parse tree for our needs.

func Parse

func Parse(rwc io.Reader) (*Node, error)

The main parse routine. Handles an io.ReadWriteCloser and returns the root of the AST.

func (*Node) Dump

func (node *Node) Dump() string

dumps the AST defined by `node` as a list of sexps. Returns a string suitable for printing.