gopkg

A toolkit for writing code generators in Golang.

Overview

gopkg provides a simple, AST-like structure for representing code declarations - FileContents.

It provides two main methods for interacting with this structure:

• Parse takes a path to a package and returns the contents of each .go file as a slice of FileContents objects.

• Generate takes a slice of FileContents objects and writes each object to .go file.

E.g.

  // pckContents has type `[]gopkg.FileContents`
  pkgContents, err := gopkg.Parse("./path/to/my/package")
  // check err

  err = gopkg.Generate(pkgContents)
  // check err

FileContents structure

Contains all package level declaration contained within a .go file, as well as information about the path to the file and it's Golang import path.

type FileContents struct {
	Filepath string
	PackageName string
	PackageImportPath string
	Imports []ImportAndAlias
	Consts []DeclVar
	Vars []DeclVar
	Types []DeclType
	Functions []DeclFunc
}

Examples:

The example_generators folder contains several toy examples of generator implementations.

See also:

servicegen - A generator for creating service interfaces and tests. resourcegen - For generating interfaces required for dependency injection.

TODO:

• Make linting method to sort FileContents

• Add DeclFunc.AdditionalImports field, which can be used to add imports at the function level

• Add DeclFunc.DocString field

• Add error checks for generation, e.g:

  • Return error when generating a func if:
    • Func name not set
    • Func args unnamed
      • Note; TypeFunc args may be unnamed... should also allow unnamed types on DeclFunc in interfaces
    • Func arg or ret arg is missing a type
  • Return error when generation a file if:
    • Filepath not set
    • PackageName not set
  • Error for TypeDecl when:
    • Name not set
    • Type not set
  • etc...

• Add linter to sanatize literals which will strip leading and trailing whitespace from all literals:

  • Remove leading whitespace from DeclFunc.BodyTmpl
  • Remove leading and trailing whitespace from all strings in FileContents
  • Maybe remove newlines from things that shouldnt have new lines? (e.g. Decl names?)

• Consider removing Import field from declaration types - it doesn't seem that this is used at all for generating; It seems like a convenience field but I'm not sure there is a scenario where this is useful