initial push

src/index.ts

@@ -0,0 +1,69 @@
+import fs from 'node:fs'
+import path from 'node:path'
+import process from 'node:process'
+
+const defaultOptions = {
+  matcher: /@import\((?<file>.+)\)(\s*?\[(?<range>\d+-\d+)\])?/g,
+  root: process.cwd(),
+}
+
+export type Options = Partial<typeof defaultOptions>
+
+export function importPlugin(md: any, options: Options = {}) {
+  // Options
+  const o = Object.assign(defaultOptions, options)
+
+  // Parser
+  function parse(code: string, alreadyVisited: string[] = []) {
+    if (!o.matcher.global) throw new Error('RegExp must be global')
+    o.matcher.lastIndex = 0 // Reset Regexp
+    const newFiles = []
+
+    while (true) {
+      const match = o.matcher.exec(code)
+      if (!match) break
+
+      // Get groups
+      const file = match.groups?.['file']?.trim()
+      if (!file) throw new Error('Regexp must expose a named group "file"')
+      const range = match.groups?.['range']
+        ?.trim()
+        .split('-')
+        .map((n) => parseInt(n))
+
+      // Load content
+      const filename = path.resolve(o.root, file)
+      if (alreadyVisited.includes(filename)) throw new Error(`cycles are not allowed, already parsed "${filename}"`)
+      newFiles.push(filename)
+      const exists = fs.existsSync(filename)
+      if (!exists) throw new Error(`cannot locate file "${filename}"`)
+      let contents = fs.readFileSync(filename, 'utf-8')
+
+      // Apply line range
+      if (range) {
+        const lines = contents.split('\n')
+        const maxLines = lines.length
+        const start = range[0]
+        const end = range[1]
+        if (start === undefined || end === undefined) throw new Error(`invalid range "${match.groups?.['range']}"`)
+        if (end < start) throw new Error(`end position "${end}" cannot be smaller than start "${start}"`)
+        if (start < 1) throw new Error(`start position "${start}" needs to be at least 1`)
+        if (end > maxLines) throw new Error(`end position "${end}" is higher than the file contents "${maxLines}"`)
+        contents = lines.slice(start - 1, end).join('\n')
+      }
+
+      // Recursion
+      contents = parse(contents, [...alreadyVisited, ...newFiles])
+
+      // Replace
+      code = code.slice(0, match.index) + contents + code.slice(match.index + match[0].length, code.length)
+    }
+
+    return code
+  }
+
+  // Mount hook
+  md.core.ruler.before('normalize', 'include', (state: any) => {
+    state.src = parse(state.src)
+  })
+}