interpolation

Documentation

Overview

FIXME(thaJeztah): remove once we are a module; the go:build directive prevents go from downgrading language version to go1.16:

Index

• Constants
• func Interpolate(config map[string]any, opts Options) (map[string]any, error)
• type Cast
• type LookupValue
• type Options
• type Path
  • func NewPath(items ...string) Path
  • func (p Path) Next(part string) Path

Constants

const PathMatchAll = "*"

PathMatchAll is a token used as part of a Path to match any key at that level in the nested structure

const PathMatchList = "[]"

PathMatchList is a token used as part of a Path to match items in a list

Functions

func Interpolate

func Interpolate(config map[string]any, opts Options) (map[string]any, error)

Interpolate replaces variables in a string with the values from a mapping

Types

type Cast

type Cast func(value string) (any, error)

Cast a value to a new type, or return an error if the value can't be cast

type LookupValue

type LookupValue func(key string) (string, bool)

LookupValue is a function which maps from variable names to values. Returns the value as a string and a bool indicating whether the value is present, to distinguish between an empty string and the absence of a value.

type Options

type Options struct {
	// LookupValue from a key
	LookupValue LookupValue
	// TypeCastMapping maps key paths to functions to cast to a type
	TypeCastMapping map[Path]Cast
	// Substitution function to use
	Substitute func(string, template.Mapping) (string, error)
}

Options supported by Interpolate

type Path

type Path string

Path is a dotted path of keys to a value in a nested mapping structure. A * section in a path will match any key in the mapping structure.

func NewPath

func NewPath(items ...string) Path

NewPath returns a new Path

func (Path) Next

func (p Path) Next(part string) Path

Next returns a new path by append part to the current path