Formatter: Extract Spacing Analyzer and Comment Helpers

javascript/packages/formatter/src/comment-helpers.ts

@@ -0,0 +1,129 @@
+import dedent from "dedent"
+
+import { isNode, isERBNode } from "@herb-tools/core"
+import { IdentityPrinter } from "@herb-tools/printer"
+import { Node, HTMLTextNode, LiteralNode } from "@herb-tools/core"
+
+/**
+ * Result of formatting an ERB comment.
+ * - `single-line`: the caller emits the text on a single line (using push or pushWithIndent)
+ * - `multi-line`: the caller emits header, indented content lines, and footer separately
+ */
+export type ERBCommentResult =
+  | { type: 'single-line'; text: string }
+  | { type: 'multi-line'; header: string; contentLines: string[]; footer: string }
+
+/**
+ * Extract the raw inner text from HTML comment children.
+ * Joins text/literal nodes by content and ERB nodes via IdentityPrinter.
+ */
+export function extractHTMLCommentContent(children: Node[]): string {
+  return children.map(child => {
+    if (isNode(child, HTMLTextNode) || isNode(child, LiteralNode)) {
+      return child.content
+    } else if (isERBNode(child)) {
+      return IdentityPrinter.print(child)
+    } else {
+      return ""
+    }
+  }).join("")
+}
+
+/**
+ * Format the inner content of an HTML comment.
+ *
+ * Handles three cases:
+ * 1. IE conditional comments (`[if ...` / `<![endif]`) — returned as-is
+ * 2. Multiline comments — re-indented with relative indent preservation
+ * 3. Single-line comments — wrapped with spaces: ` content `
+ *
+ * Returns null for IE conditional comments to signal the caller
+ * should emit the raw content without reformatting.
+ *
+ * @param rawInner - The joined children content string (may be empty)
+ * @param indentWidth - Number of spaces per indent level
+ * @returns The formatted inner string, or null if rawInner is empty-ish
+ */
+export function formatHTMLCommentInner(rawInner: string, indentWidth: number): string {
+  if (!rawInner && rawInner !== "") return ""
+
+  const trimmedInner = rawInner.trim()
+
+  if (trimmedInner.startsWith('[if ') && trimmedInner.endsWith('<![endif]')) {
+    return rawInner
+  }
+
+  const hasNewlines = rawInner.includes('\n')
+
+  if (hasNewlines) {
+    const lines = rawInner.split('\n')
+    const childIndent = " ".repeat(indentWidth)
+    const firstLineHasContent = lines[0].trim() !== ''
+
+    if (firstLineHasContent && lines.length > 1) {
+      const contentLines = lines.map(line => line.trim()).filter(line => line !== '')
+      return '\n' + contentLines.map(line => childIndent + line).join('\n') + '\n'
+    } else {
+      const contentLines = lines.filter((line, index) => {
+        return line.trim() !== '' && !(index === 0 || index === lines.length - 1)
+      })
+
+      const minIndent = contentLines.length > 0 ? Math.min(...contentLines.map(line => line.length - line.trimStart().length)) : 0
+
+      const processedLines = lines.map((line, index) => {
+        const trimmedLine = line.trim()
+
+        if ((index === 0 || index === lines.length - 1) && trimmedLine === '') {
+          return line
+        }
+
+        if (trimmedLine !== '') {
+          const currentIndent = line.length - line.trimStart().length
+          const relativeIndent = Math.max(0, currentIndent - minIndent)
+
+          return childIndent + " ".repeat(relativeIndent) + trimmedLine
+        }
+
+        return line
+      })
+
+      return processedLines.join('\n')
+    }
+  } else {
+    return ` ${rawInner.trim()} `
+  }
+}
+
+/**
+ * Format an ERB comment into either a single-line or multi-line result.
+ *
+ * @param open - The opening tag (e.g. "<%#")
+ * @param content - The raw content string between open/close tags
+ * @param close - The closing tag (e.g. "%>")
+ * @returns A discriminated union describing how to render the comment
+ */
+export function formatERBCommentLines(open: string, content: string, close: string): ERBCommentResult {
+  const contentLines = content.split("\n")
+  const contentTrimmedLines = content.trim().split("\n")
+
+  if (contentLines.length === 1 && contentTrimmedLines.length === 1) {
+    const startsWithSpace = content[0] === " "
+    const before = startsWithSpace ? "" : " "
+
+    return { type: 'single-line', text: open + before + content.trimEnd() + ' ' + close }
+  }
+
+  if (contentTrimmedLines.length === 1) {
+    return { type: 'single-line', text: open + ' ' + content.trim() + ' ' + close }
+  }
+
+  const firstLineEmpty = contentLines[0].trim() === ""
+  const dedentedContent = dedent(firstLineEmpty ? content : content.trimStart())
+
+  return {
+    type: 'multi-line',
+    header: open,
+    contentLines: dedentedContent.split("\n"),
+    footer: close
+  }
+}

javascript/packages/formatter/src/format-helpers.ts

@@ -498,6 +498,21 @@ export function isHerbDisableComment(node: Node): boolean {
   return trimmed.startsWith("herb:disable")
 }
 
+/**
+ * Check if children contain a leading herb:disable comment (after optional whitespace)
+ */
+export function hasLeadingHerbDisable(children: Node[]): boolean {
+  for (const child of children) {
+    if (isNode(child, WhitespaceNode) || (isNode(child, HTMLTextNode) && child.content.trim() === "")) {
+      continue
+    }
+
+    return isNode(child, ERBContentNode) && isHerbDisableComment(child)
+  }
+
+  return false
+}
+
 /**
  * Check if a text node is YAML frontmatter (starts and ends with ---)
  */