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|
package main
import (
"bytes"
"encoding/json"
"fmt"
"maps"
"regexp"
"slices"
"strconv"
"strings"
)
// genNix returns a generated Nix function of lib (and any imports) that returns the options for root
func genNix(root *structType, schema string) ([]byte, error) {
imports := nixImports(root)
slices.Sort(imports)
args := append([]string{"lib"}, slices.Compact(imports)...)
var w bytes.Buffer
fmt.Fprintf(&w, `# Code generated by gen from %s; DO NOT EDIT.
{ %s }:
let
inherit (lib) mkOption types;
in
`, schema, strings.Join(args, ", "))
writeNixStruct(&w, root, "")
w.WriteString("\n")
return w.Bytes(), nil
}
// nixImports returns the names imported by every field under st, which may contain duplicates
func nixImports(st *structType) []string {
var names []string
for _, f := range st.fields {
if f.nixSkip {
continue
}
if f.nested != nil {
names = append(names, nixImports(f.nested)...)
continue
}
names = append(names, f.nixImports...)
}
return names
}
// inNix reports whether f is part of the Nix options.
// It's left out if it's skipped, or if it's a struct with nothing in it that isn't.
func inNix(f *field) bool {
if f.nixSkip {
return false
}
if f.nested == nil {
return true
}
return slices.ContainsFunc(f.nested.fields, inNix)
}
// writeNixStruct writes st as an attribute set of options, where indent is the indent of the closing brace
func writeNixStruct(w *bytes.Buffer, st *structType, indent string) {
w.WriteString("{\n")
innerIndent := indent + " "
isRoot := indent == ""
first := true
for _, f := range st.fields {
if !inNix(f) {
continue
}
// A blank line goes between top-level entries, and before any nested attribute set
if !first && (isRoot || f.nested != nil) {
w.WriteString("\n")
}
first = false
fmt.Fprintf(w, "%s%s = ", innerIndent, nixKey(f.label))
if f.nested != nil {
writeNixStruct(w, f.nested, innerIndent)
w.WriteString(";\n")
continue
}
writeNixOption(w, f, innerIndent)
}
w.WriteString(indent + "}")
}
// writeNixOption writes the mkOption for f, where indent is the indent of the closing brace
func writeNixOption(w *bytes.Buffer, f *field, indent string) {
typ, note := nixFieldType(f)
apply := nixFieldApply(f)
if f.optional {
typ = "types.nullOr " + paren(typ)
if apply != "" {
apply = "lib.mapNullable " + paren(apply)
}
}
innerIndent := indent + " "
w.WriteString("mkOption {\n")
if note != "" {
fmt.Fprintf(w, "%s# %s\n", innerIndent, note)
}
fmt.Fprintf(w, "%stype = %s;\n", innerIndent, typ)
if def, ok := nixFieldDefault(f); ok {
fmt.Fprintf(w, "%sdefault = %s;\n", innerIndent, def)
}
if apply != "" {
fmt.Fprintf(w, "%sapply = %s;\n", innerIndent, apply)
}
if f.doc != "" {
fmt.Fprintf(w, "%sdescription = %s;\n", innerIndent, nixString(f.doc))
}
fmt.Fprintf(w, "%s};\n", indent)
}
// nixFieldDefault returns the default for f: @nix(default) if set, otherwise the schema default,
// otherwise null for an optional field
func nixFieldDefault(f *field) (string, bool) {
switch {
case f.hasNixDefault:
return nixValue(f.nixDefault), true
case f.hasDefault:
return nixValue(f.defaultValue), true
case f.optional:
return "null", true
default:
return "", false
}
}
// nixFieldType returns the Nix type of f, and a note to comment on the option if the type doesn't check everything.
// On a list, @nix(type) replaces the whole list type.
func nixFieldType(f *field) (typ, note string) {
if !f.isList {
return nixScalarType(f.scalar)
}
if f.nixListType != "" {
return f.nixListType, ""
}
elemType, note := nixScalarType(f.scalar)
return "types.listOf " + paren(elemType), note
}
// nixFieldApply returns the apply function for f.
// On a list, @nix(type) or @nix(apply) on the field replaces the element's apply, otherwise the element's is mapped over the list.
func nixFieldApply(f *field) string {
if !f.isList {
return f.scalar.nixApply
}
if f.nixListType != "" || f.nixListApply != "" {
return f.nixListApply
}
if f.scalar.nixApply != "" {
return "map " + paren(f.scalar.nixApply)
}
return ""
}
// nixScalarType returns the Nix type of s, and a note to comment on the option if the type doesn't check everything
func nixScalarType(s scalar) (typ, note string) {
if s.nixType != "" {
return s.nixType, ""
}
if len(s.enum) > 0 {
values := make([]string, len(s.enum))
for idx, e := range s.enum {
values[idx] = nixValue(e)
}
return "types.enum [ " + strings.Join(values, " ") + " ]", ""
}
switch s.kind {
case kindBool:
return "types.bool", ""
case kindInt:
return nixIntType(s), ""
case kindFloat:
return withRangeCheck("types.float", s), ""
case kindNumber:
return withRangeCheck("types.number", s), ""
default:
return nixStringType(s)
}
}
// nixIntType returns the Nix type of an int, using the built-in ranged types where possible
func nixIntType(s scalar) string {
lower, upper := intBounds(s)
switch {
case lower != nil && upper != nil:
return fmt.Sprintf("types.ints.between %s %s", nixInt(*lower), nixInt(*upper))
case lower != nil && *lower == 0:
return "types.ints.unsigned"
case lower != nil && *lower == 1:
return "types.ints.positive"
default:
return withRangeCheck("types.int", s)
}
}
// nixStringType returns the Nix type of a string, and a note if its regexes can't all be checked in Nix
func nixStringType(s scalar) (typ, note string) {
if len(s.regexes) == 0 {
if s.notEmpty {
return "types.nonEmptyStr", ""
}
return "types.str", ""
}
// types.strMatching only takes a single regex, so only the first is checked
re, ok := ereFull(s.regexes[0].pattern)
if !ok {
return "types.str", fmt.Sprintf("%q can't be expressed as a POSIX regex; checked by the application only.", s.regexes[0].pattern)
}
if len(s.regexes) > 1 {
note = "Only the first regex is checked here; all are checked by the application."
}
return "types.strMatching " + nixString(re), note
}
// withRangeCheck adds a check of the scalar's bounds to base, if it has any
func withRangeCheck(base string, s scalar) string {
var conds []string
if s.min != nil {
op := ">"
if s.min.inclusive {
op = ">="
}
conds = append(conds, fmt.Sprintf("x %s %s", op, s.min.value))
}
if s.max != nil {
op := "<"
if s.max.inclusive {
op = "<="
}
conds = append(conds, fmt.Sprintf("x %s %s", op, s.max.value))
}
if len(conds) == 0 {
return base
}
return fmt.Sprintf("types.addCheck %s (x: %s)", base, strings.Join(conds, " && "))
}
// nixInt returns n as a Nix int, where negative numbers need parentheses to be a function argument
func nixInt(n int64) string {
if n < 0 {
return "(" + strconv.FormatInt(n, 10) + ")"
}
return strconv.FormatInt(n, 10)
}
// re2Only matches RE2 syntax that POSIX ERE doesn't have: class escapes like \d, groups with flags like (?i), and lazy quantifiers
var re2Only = regexp.MustCompile(`\\[dDwWsSbBpPQEAzZx]|\(\?|[*+?}]\?`)
// ereFull converts an RE2 regex, which matches anywhere in a string, to a POSIX ERE that must match the whole string, as types.strMatching expects.
// It returns false if the regex can't be converted.
func ereFull(re string) (string, bool) {
if re2Only.MatchString(re) {
return "", false
}
anchoredStart := strings.HasPrefix(re, "^")
anchoredEnd := strings.HasSuffix(re, "$") && !strings.HasSuffix(re, `\$`)
// With an alternation, an anchor only applies to one side, so it can't just be stripped
if strings.Contains(re, "|") {
if anchoredStart || anchoredEnd {
return "", false
}
return ".*(" + re + ").*", true
}
if anchoredStart {
re = strings.TrimPrefix(re, "^")
} else {
re = ".*" + re
}
if anchoredEnd {
re = strings.TrimSuffix(re, "$")
} else {
re += ".*"
}
return re, true
}
// paren wraps a Nix expression in parentheses if it has spaces, so it can be used as a function argument
func paren(s string) string {
alreadyWrapped := strings.HasPrefix(s, "(") && strings.HasSuffix(s, ")")
if strings.Contains(s, " ") && !alreadyWrapped {
return "(" + s + ")"
}
return s
}
// nixIdent matches a valid Nix identifier
var nixIdent = regexp.MustCompile(`^[a-zA-Z_][a-zA-Z0-9_'-]*$`)
// nixReserved are bound by the generated file itself
var nixReserved = map[string]bool{
"lib": true,
"mkOption": true,
"types": true,
}
var nixKeywords = map[string]bool{
"assert": true,
"else": true,
"if": true,
"in": true,
"inherit": true,
"let": true,
"or": true,
"rec": true,
"then": true,
"with": true,
}
// nixKey returns k as an attribute name, quoting it if needed
func nixKey(k string) string {
if nixIdent.MatchString(k) && !nixKeywords[k] {
return k
}
return nixString(k)
}
var nixStringEscaper = strings.NewReplacer(
`\`, `\\`,
`"`, `\"`,
"${", `\${`,
"\n", `\n`,
"\r", `\r`,
"\t", `\t`,
)
// nixString returns s as a quoted Nix string
func nixString(s string) string {
return `"` + nixStringEscaper.Replace(s) + `"`
}
// nixValue returns a decoded value as a Nix expression
func nixValue(v any) string {
switch v := v.(type) {
case nil:
return "null"
case string:
return nixString(v)
case bool:
return strconv.FormatBool(v)
case json.Number:
return nixNumber(v)
case []any:
if len(v) == 0 {
return "[ ]"
}
items := make([]string, len(v))
for idx, item := range v {
items[idx] = nixValue(item)
}
return "[ " + strings.Join(items, " ") + " ]"
case map[string]any:
var attrs strings.Builder
attrs.WriteString("{ ")
for _, key := range slices.Sorted(maps.Keys(v)) {
fmt.Fprintf(&attrs, "%s = %s; ", nixKey(key), nixValue(v[key]))
}
attrs.WriteString("}")
return attrs.String()
default:
return fmt.Sprint(v)
}
}
// nixNumber returns n as a Nix number.
// Nix has no exponent notation, and a negative number needs parentheses to be a list item or function argument.
func nixNumber(n json.Number) string {
s := n.String()
if strings.ContainsAny(s, "eE") {
f, _ := n.Float64()
s = strconv.FormatFloat(f, 'f', -1, 64)
// Keep it a float in Nix
if !strings.Contains(s, ".") {
s += ".0"
}
}
if strings.HasPrefix(s, "-") {
return "(" + s + ")"
}
return s
}
|