gogen

README

gogen

Code generation template language

What

A template language that has a template per type and works similar to the visitor pattern. Each node that needs to be rendered does that by rendering its own template defined by its type.

Example

main visitor:

pkg.AST type:
  Title ${.Title}
  {for c, item in .Items}
    ${c}: @{item}
  {end}

pkg.Item type:
  ${.Label} (${.Count})

Syntax documentation

Syntax documentation

Why

So far when I had to generate some code I used two aproaches:

Template language

With template languages like jinja, handlebars or whatever you can easily generate code from an AST or a similar composite datastructure.

Although it works pretty well for simpler generators it ends up in a mess when the generated code is getting more complex and a lot of logic needs to be either in the AST or template language.

Another problem is reusability. Although most template languages support macros or at least includes it's usually unintuitive and makes the code look clutered.

Visitor pattern

The second aproach is to let a visitor traverse the AST and output code for each node. Usually i have different visitors to generate different representations of the same node.

This works very well for complex code but is not well suited for bigger chunks of simple code and also quite a bit of boilerplate is needed.

GoGen approach

Trying to eliminate the shortcomings i combined the two approaches. Instead of creating one template that iterates trough the whole AST a small template is created for each node.

So when a node is visited, it's template is executed and the result is inserted.

Documentation

Index

• func Execute(ast *ast.AST, model interface{}, options ...Option) (string, error)
• func ExecuteDetailed(a *ast.AST, model interface{}, options ...Option) (string, *ggerr.MultiError)
• func Parse(code, source string, imports func(i string) (string, string, error)) (*ast.AST, error)
• func ParseDetailed(code, source string, imports func(i string) (string, string, error)) (*ast.AST, *ggerr.MultiError)
• type Option
  • func FilterOption(name string, f interface{}) Option
  • func WithVar(name string, f interface{}) Option

Functions

func Execute

func Execute(ast *ast.AST, model interface{}, options ...Option) (string, error)

func ExecuteDetailed

func ExecuteDetailed(a *ast.AST, model interface{}, options ...Option) (string, *ggerr.MultiError)

func Parse

func Parse(code, source string, imports func(i string) (string, string, error)) (*ast.AST, error)

Parse a gogen template

func ParseDetailed

func ParseDetailed(code, source string, imports func(i string) (string, string, error)) (*ast.AST, *ggerr.MultiError)

ParseDetailed will always return an error object which contains details about all found errors

Types

type Option

type Option interface {
	// contains filtered or unexported methods
}

func FilterOption

func FilterOption(name string, f interface{}) Option

func WithVar

func WithVar(name string, f interface{}) Option