Files
genqlient/generate/template.go
T
Ben Kraft f72933fa0e Refactor import-loading to simplify the type-generation code (#101)
## Summary:
genqlient has some code (`imports.go`) dedicated to tracking which
imports we need and avoiding conflicts, as well as converting a
(restricted) Go expression like `map[string]github.com/me/mypkg.MyType`
to an import (`github.com/me/mypkg`) and a type-reference
(`map[string]mypkg.MyType`) to be used in the context of that import,
and at least making some attempt to track conflicts.  (Right now the
conflict-avoidance is not very smart, and not very well tested, but it
comes up rarely anyway.)  Sadly, that code was a bit cumbersome to use,
because you had to first register the imports (typically from
`convert.go`), then use them (often from the template).

In this commit I refactor the order we write things in order to allow a
significant simplification of how we import; in particular we no longer
have to guess in advance what imports which template will need; it can
just do `{{ref <expr>}}` as before, and it just works.  To do this, I:
- changed the importer to have only one API, which adds the import if
  needed, and returns the reference either way
- added a check that we don't add imports after they're written
- reorganized the toplevel templates a bit to make sure that check never
  fires; we now generate all the types and operations, then write the
  imports and glue it all together
This removes a bunch of silly code, and should simplify the process of
adding custom (un)marshalers (#38).

While I was at it, I put the documentation of what expressions we
support in a more visible place, and added a type-assertion that your
custom context type implements context.Context (if applicable).

## Test plan:
make check


Author: benjaminjkraft

Reviewers: StevenACoffman, dnerdy, aberkan, jvoll, mahtabsabet, MiguelCastillo

Required Reviewers: 

Approved By: StevenACoffman, dnerdy

Checks:  Test (1.17),  Test (1.16),  Test (1.15),  Test (1.14),  Lint,  Test (1.17),  Test (1.16),  Test (1.15),  Test (1.14),  Lint

Pull Request URL: https://github.com/Khan/genqlient/pull/101
2021-09-16 18:09:32 -07:00

60 lines
1.3 KiB
Go

package generate
import (
"io"
"path/filepath"
"runtime"
"strings"
"text/template"
)
var (
// TODO(benkraft): Embed templates into the binary, see
// https://github.com/Khan/genqlient/issues/9.
_, thisFilename, _, _ = runtime.Caller(0)
thisDir = filepath.Dir(thisFilename)
)
func repeat(n int, s string) string {
var builder strings.Builder
for i := 0; i < n; i++ {
builder.WriteString(s)
}
return builder.String()
}
func intRange(n int) []int {
ret := make([]int, n)
for i := 0; i < n; i++ {
ret[i] = i
}
return ret
}
func sub(x, y int) int { return x - y }
// render executes the given template with the funcs from this generator.
func (g *generator) render(tmplRelFilename string, w io.Writer, data interface{}) error {
tmpl := g.templateCache[tmplRelFilename]
if tmpl == nil {
absFilename := filepath.Join(thisDir, tmplRelFilename)
funcMap := template.FuncMap{
"ref": g.ref,
"repeat": repeat,
"intRange": intRange,
"sub": sub,
}
var err error
tmpl, err = template.New(tmplRelFilename).Funcs(funcMap).ParseFiles(absFilename)
if err != nil {
return errorf(nil, "could not load template %v: %v", absFilename, err)
}
g.templateCache[tmplRelFilename] = tmpl
}
err := tmpl.Execute(w, data)
if err != nil {
return errorf(nil, "could not render template: %v", err)
}
return nil
}