refactor: decoding source files

src/decode/validation.ts

@@ -0,0 +1,97 @@
+import type { ArrayHeaderInfo, Delimiter, Depth, ResolvedDecodeOptions } from '../types'
+import type { LineCursor } from './scanner'
+import { COLON, LIST_ITEM_PREFIX } from '../constants'
+
+/**
+ * Asserts that the actual count matches the expected count in strict mode.
+ *
+ * @param actual The actual count
+ * @param expected The expected count
+ * @param itemType The type of items being counted (e.g., 'list array items', 'tabular rows')
+ * @param options Decode options
+ * @throws RangeError if counts don't match in strict mode
+ */
+export function assertExpectedCount(
+  actual: number,
+  expected: number,
+  itemType: string,
+  options: ResolvedDecodeOptions,
+): void {
+  if (options.strict && actual !== expected) {
+    throw new RangeError(`Expected ${expected} ${itemType}, but got ${actual}`)
+  }
+}
+
+/**
+ * Validates that there are no extra list items beyond the expected count.
+ *
+ * @param cursor The line cursor
+ * @param itemDepth The expected depth of items
+ * @param expectedCount The expected number of items
+ * @throws RangeError if extra items are found
+ */
+export function validateNoExtraListItems(
+  cursor: LineCursor,
+  itemDepth: Depth,
+  expectedCount: number,
+): void {
+  if (cursor.atEnd())
+    return
+
+  const nextLine = cursor.peek()
+  if (nextLine && nextLine.depth === itemDepth && nextLine.content.startsWith(LIST_ITEM_PREFIX)) {
+    throw new RangeError(`Expected ${expectedCount} list array items, but found more`)
+  }
+}
+
+/**
+ * Checks if a line represents a data row (as opposed to a key-value pair) in a tabular array.
+ *
+ * @param content The line content
+ * @param delimiter The delimiter used in the table
+ * @returns true if the line is a data row, false if it's a key-value pair
+ */
+export function isDataRow(content: string, delimiter: Delimiter): boolean {
+  const colonPos = content.indexOf(COLON)
+  const delimiterPos = content.indexOf(delimiter)
+
+  // No colon = definitely a data row
+  if (colonPos === -1) {
+    return true
+  }
+
+  // Has delimiter and it comes before colon = data row
+  if (delimiterPos !== -1 && delimiterPos < colonPos) {
+    return true
+  }
+
+  // Colon before delimiter or no delimiter = key-value pair
+  return false
+}
+
+/**
+ * Validates that there are no extra tabular rows beyond the expected count.
+ *
+ * @param cursor The line cursor
+ * @param rowDepth The expected depth of rows
+ * @param header The array header info containing length and delimiter
+ * @throws RangeError if extra rows are found
+ */
+export function validateNoExtraTabularRows(
+  cursor: LineCursor,
+  rowDepth: Depth,
+  header: ArrayHeaderInfo,
+): void {
+  if (cursor.atEnd())
+    return
+
+  const nextLine = cursor.peek()
+  if (
+    nextLine
+    && nextLine.depth === rowDepth
+    && !nextLine.content.startsWith(LIST_ITEM_PREFIX)
+    && isDataRow(nextLine.content, header.delimiter)
+  ) {
+    throw new RangeError(`Expected ${header.length} tabular rows, but found more`)
+  }
+}