86 lines
1.8 KiB
Go
86 lines
1.8 KiB
Go
package builder
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import (
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"bufio"
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"bytes"
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"errors"
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"fmt"
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"os"
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"gopkg.in/yaml.v3"
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)
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func processFrontmatter(p string) (*FrontMatter, int, error) {
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f, l, err := readFrontmatter(p)
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if err != nil {
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return nil, l, err
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}
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var meta FrontMatter
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// Parse YAML
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if err := yaml.Unmarshal(f, &meta); err != nil {
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return nil, l, fmt.Errorf("yaml frontmatter could not be parsed: %w", err)
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}
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return &meta, l, nil
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}
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// readFrontmatter reads the file at `path` and scans
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// it for --- delimited frontmatter. It does not attempt
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// to parse the data, it only scans for the delimiters.
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// It returns the frontmatter contents as a byte array
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// and its length in lines.
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func readFrontmatter(path string) ([]byte, int, error) {
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file, err := os.Open(path)
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if err != nil {
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return nil, 0, err
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}
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defer file.Close()
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lines := make([]string, 0, 10)
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s := bufio.NewScanner(file)
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i := 0
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delims := 0
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for s.Scan() {
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l := s.Text()
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if l == `---` {
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if i == 1 && delims == 0 {
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// if --- is not the first line, we
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// assume the file does not contain frontmatter
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// fmt.Println("Delimiter first line")
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return nil, 0, nil
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}
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delims += 1
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i += 1
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if delims == 2 {
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break
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}
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} else {
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if i == 0 {
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return nil, 0, nil
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}
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lines = append(lines, l)
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i += 1
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}
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}
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// check whether any errors occurred while scanning
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if err := s.Err(); err != nil {
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return nil, 0, err
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}
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if delims == 2 {
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l := len(lines)
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if l == 0 {
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// no valid frontmatter
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return nil, 0, errors.New("frontmatter cannot be empty")
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}
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// convert to byte array
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var b bytes.Buffer
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for _, line := range lines {
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b.WriteString(line + "\n")
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}
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return b.Bytes(), l, nil
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} else {
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// not enough delimiters, don't
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// treat as frontmatter
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s := fmt.Sprintf("%s: frontmatter is missing closing delimiter", path)
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return nil, 0, errors.New(s)
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}
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}
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