From 2d4c46c975eb916dc622cc729a1a8d397582a76f Mon Sep 17 00:00:00 2001
From: David Sherret <dsherret@users.noreply.github.com>
Date: Mon, 28 Nov 2022 17:28:54 -0500
Subject: refactor: create util folder, move nap_sym to napi/sym, move
 http_cache to cache folder (#16857)

---
 cli/util/text_encoding.rs | 162 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 cli/util/text_encoding.rs

(limited to 'cli/util/text_encoding.rs')

diff --git a/cli/util/text_encoding.rs b/cli/util/text_encoding.rs
new file mode 100644
index 000000000..c16a1289d
--- /dev/null
+++ b/cli/util/text_encoding.rs
@@ -0,0 +1,162 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+
+use encoding_rs::*;
+use std::borrow::Cow;
+use std::io::Error;
+use std::io::ErrorKind;
+
+pub const BOM_CHAR: char = '\u{FEFF}';
+
+/// Attempts to detect the character encoding of the provided bytes.
+///
+/// Supports UTF-8, UTF-16 Little Endian and UTF-16 Big Endian.
+pub fn detect_charset(bytes: &'_ [u8]) -> &'static str {
+  const UTF16_LE_BOM: &[u8] = b"\xFF\xFE";
+  const UTF16_BE_BOM: &[u8] = b"\xFE\xFF";
+
+  if bytes.starts_with(UTF16_LE_BOM) {
+    "utf-16le"
+  } else if bytes.starts_with(UTF16_BE_BOM) {
+    "utf-16be"
+  } else {
+    // Assume everything else is utf-8
+    "utf-8"
+  }
+}
+
+/// Attempts to convert the provided bytes to a UTF-8 string.
+///
+/// Supports all encodings supported by the encoding_rs crate, which includes
+/// all encodings specified in the WHATWG Encoding Standard, and only those
+/// encodings (see: <https://encoding.spec.whatwg.org/>).
+pub fn convert_to_utf8<'a>(
+  bytes: &'a [u8],
+  charset: &'_ str,
+) -> Result<Cow<'a, str>, Error> {
+  match Encoding::for_label(charset.as_bytes()) {
+    Some(encoding) => encoding
+      .decode_without_bom_handling_and_without_replacement(bytes)
+      .ok_or_else(|| ErrorKind::InvalidData.into()),
+    None => Err(Error::new(
+      ErrorKind::InvalidInput,
+      format!("Unsupported charset: {}", charset),
+    )),
+  }
+}
+
+/// Strips the byte order mark from the provided text if it exists.
+pub fn strip_bom(text: &str) -> &str {
+  if text.starts_with(BOM_CHAR) {
+    &text[BOM_CHAR.len_utf8()..]
+  } else {
+    text
+  }
+}
+
+static SOURCE_MAP_PREFIX: &str =
+  "//# sourceMappingURL=data:application/json;base64,";
+
+pub fn source_map_from_code(code: &str) -> Option<Vec<u8>> {
+  let last_line = code.rsplit(|u| u == '\n').next()?;
+  if last_line.starts_with(SOURCE_MAP_PREFIX) {
+    let input = last_line.split_at(SOURCE_MAP_PREFIX.len()).1;
+    let decoded_map = base64::decode(input)
+      .expect("Unable to decode source map from emitted file.");
+    Some(decoded_map)
+  } else {
+    None
+  }
+}
+
+pub fn code_without_source_map(mut code: String) -> String {
+  if let Some(last_line_index) = code.rfind('\n') {
+    if code[last_line_index + 1..].starts_with(SOURCE_MAP_PREFIX) {
+      code.truncate(last_line_index + 1);
+      code
+    } else {
+      code
+    }
+  } else {
+    code
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  fn test_detection(test_data: &[u8], expected_charset: &str) {
+    let detected_charset = detect_charset(test_data);
+    assert_eq!(
+      expected_charset.to_lowercase(),
+      detected_charset.to_lowercase()
+    );
+  }
+
+  #[test]
+  fn test_detection_utf8_no_bom() {
+    let test_data = "Hello UTF-8 it is \u{23F0} for Deno!"
+      .to_owned()
+      .into_bytes();
+    test_detection(&test_data, "utf-8");
+  }
+
+  #[test]
+  fn test_detection_utf16_little_endian() {
+    let test_data = b"\xFF\xFEHello UTF-16LE".to_owned().to_vec();
+    test_detection(&test_data, "utf-16le");
+  }
+
+  #[test]
+  fn test_detection_utf16_big_endian() {
+    let test_data = b"\xFE\xFFHello UTF-16BE".to_owned().to_vec();
+    test_detection(&test_data, "utf-16be");
+  }
+
+  #[test]
+  fn test_decoding_unsupported_charset() {
+    let test_data = Vec::new();
+    let result = convert_to_utf8(&test_data, "utf-32le");
+    assert!(result.is_err());
+    let err = result.expect_err("Err expected");
+    assert!(err.kind() == ErrorKind::InvalidInput);
+  }
+
+  #[test]
+  fn test_decoding_invalid_utf8() {
+    let test_data = b"\xFE\xFE\xFF\xFF".to_vec();
+    let result = convert_to_utf8(&test_data, "utf-8");
+    assert!(result.is_err());
+    let err = result.expect_err("Err expected");
+    assert!(err.kind() == ErrorKind::InvalidData);
+  }
+
+  #[test]
+  fn test_source_without_source_map() {
+    run_test("", "");
+    run_test("\n", "\n");
+    run_test("\r\n", "\r\n");
+    run_test("a", "a");
+    run_test("a\n", "a\n");
+    run_test("a\r\n", "a\r\n");
+    run_test("a\r\nb", "a\r\nb");
+    run_test("a\nb\n", "a\nb\n");
+    run_test("a\r\nb\r\n", "a\r\nb\r\n");
+    run_test(
+      "test\n//# sourceMappingURL=data:application/json;base64,test",
+      "test\n",
+    );
+    run_test(
+      "test\r\n//# sourceMappingURL=data:application/json;base64,test",
+      "test\r\n",
+    );
+    run_test(
+      "\n//# sourceMappingURL=data:application/json;base64,test",
+      "\n",
+    );
+
+    fn run_test(input: &str, output: &str) {
+      assert_eq!(code_without_source_map(input.to_string()), output);
+    }
+  }
+}
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