parser

Documentation

Overview

Package parser implements a parser and parse tree dumper for Dockerfiles.

Index

• Constants
• type Directive
  • func NewDefaultDirective() *Directive
• type Node
  • func NodeFromLabels(labels map[string]string) *Node
  • func (node *Node) AddChild(child *Node, startLine, endLine int)
  • func (node *Node) Dump() string
• type Result
  • func Parse(rwc io.Reader) (*Result, error)
  • func (r *Result) PrintWarnings(out io.Writer)

Constants

const DefaultEscapeToken = '\\'

DefaultEscapeToken is the default escape token

Types

type Directive

type Directive struct {
	// contains filtered or unexported fields
}

Directive is the structure used during a build run to hold the state of parsing directives.

func NewDefaultDirective

func NewDefaultDirective() *Directive

NewDefaultDirective returns a new Directive with the default escapeToken token

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
	Flags      []string        // only top Node should have this set
	StartLine  int             // the line in the original dockerfile where the node begins
	// contains filtered or unexported fields
}

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 NodeFromLabels

func NodeFromLabels(labels map[string]string) *Node

NodeFromLabels returns a Node for the injected labels

func (*Node) AddChild

func (node *Node) AddChild(child *Node, startLine, endLine int)

AddChild adds a new child node, and updates line information

func (*Node) Dump

func (node *Node) Dump() string

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

type Result

type Result struct {
	AST         *Node
	EscapeToken rune
	// TODO @jhowardmsft - see https://github.com/moby/moby/issues/34617
	// This next field will be removed in a future update for LCOW support.
	OS       string
	Warnings []string
}

Result is the result of parsing a Dockerfile

func Parse

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

Parse reads lines from a Reader, parses the lines into an AST and returns the AST and escape token

func (*Result) PrintWarnings

func (r *Result) PrintWarnings(out io.Writer)

PrintWarnings to the writer