89 lines
2.7 KiB
Go
89 lines
2.7 KiB
Go
package fejkdata
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import (
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"encoding/json"
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"fmt"
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"strings"
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)
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// Template is an inline template compiled, referenced and validated against a
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// generator's loaded data once, ready to render many times with [Template.Fake].
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// It is safe for concurrent use: Fake serializes on its generator's lock, so a
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// seeded sequence is reproducible only when a generator — and its templates — are
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// drawn from one goroutine.
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type Template struct {
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g *Generator
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n node
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}
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// Fake renders the template with one draw.
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func (t *Template) Fake() string {
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t.g.mu.Lock()
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defer t.g.mu.Unlock()
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return render(t.g.rand, t.n, nil)
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}
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// NewTemplate compiles an inline template — a format string or a JSON value — and
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// binds its references against the loaded tree, so repeated renders pay the
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// compile and validation once. It shares [New]'s guarantees: a bad template errors
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// here, and rendering cannot fail.
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func (f *Generator) NewTemplate(input string) (*Template, error) {
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n, err := compileInput(input)
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if err != nil {
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return nil, fmt.Errorf("fejkdata: %w", err)
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}
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scope := inlineScope(n)
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if err := linkNodeRefs(scope, f.categories); err != nil {
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return nil, fmt.Errorf("fejkdata: %w", err)
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}
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if err := checkScope(scope); err != nil {
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return nil, fmt.Errorf("fejkdata: %w", err)
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}
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return &Template{g: f, n: n}, nil
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}
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// FakeTemplate compiles and renders an inline template in one call. It is
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// [NewTemplate] then [Template.Fake]; to render the same template many times, hold
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// the *Template and call its Fake.
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func (f *Generator) FakeTemplate(input string) (string, error) {
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t, err := f.NewTemplate(input)
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if err != nil {
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return "", err
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}
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return t.Fake(), nil
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}
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// compileInput compiles an inline template: a JSON value, or a bare format string
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// when the input is not JSON.
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func compileInput(input string) (node, error) {
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var raw any
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if err := json.Unmarshal([]byte(input), &raw); err != nil {
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return compile(input)
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}
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if trimmed := strings.TrimSpace(input); trimmed != input {
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return nil, fmt.Errorf("a JSON template may not be padded with spaces, which a format string would render; write %s", trimmed)
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}
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return compile(raw)
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}
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// linkNodeRefs binds the references in an inline node's templates against the
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// loaded tree.
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func linkNodeRefs(scope nodeScope, root map[string]node) error {
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return scope(func(path string, m node) error {
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t, ok := m.(*template)
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if !ok {
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return nil
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}
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for _, name := range refTokens(t.format) {
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sigil, rest, err := refShape(name)
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if err != nil {
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return fmt.Errorf("%s: reference {%s}: %w", path, name, err)
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}
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if sigil != "/" {
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return fmt.Errorf("%s: reference {%s}: an inline template has no folder; write {/%s}", path, name, rest)
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}
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}
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return linkTemplateRefs(nil, path, t, root)
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})
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}
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