Fixes parsing of imports in multi-line string literals.

src/workerd/api/pyodide/pyodide-test.c++

@@ -115,5 +115,18 @@ KJ_TEST("supports backslash") {
  KJ_REQUIRE(result[5] == "c");
 }
 
+KJ_TEST("multiline-strings ignored") {
+ auto files = kj::heapArrayBuilder<kj::String>(4);
+ files.add(kj::str("FOO=\"\"\"\nimport x\nfrom y import z\n\"\"\""));
+ files.add(kj::str("FOO=\'\'\'\nimport f\nfrom g import z\n\'\'\'"));
+ files.add(kj::str("FOO = \"\\\nimport b \\\n\""));
+ files.add(kj::str("FOO=\"\"\" \nimport x\nfrom y import z\n\"\"\""));
+ auto result = pyodide::ArtifactBundler::parsePythonScriptImports(files.finish());
+ KJ_REQUIRE(result.size() == 0);
+}
+
+// TODO: test multi-line followed by imports, and imports in between multi-line strings, etc. Also imports
+// after single string literals.
+
 } // namespace
 } // namespace workerd::api

src/workerd/api/pyodide/pyodide.c++

@@ -207,12 +207,14 @@ kj::Array<kj::String> ArtifactBundler::parsePythonScriptImports(kj::Array<kj::St
 
  int i = 0;
  while (i < file.size()) {
- auto keywordToParse = file[i] == 'i' ? "import"_kj : "from"_kj;
  switch (file[i]) {
  case 'i':
- case 'f':
+ case 'f': {
+ auto keywordToParse = file[i] == 'i' ? "import"_kj : "from"_kj;
  if (!parseKeyword(file, keywordToParse, i)) {
- i += skipUntil(file, {'\n', '\r'}, i);
+ // We cannot simply skip the current char here, doing so would mean that
+ // `iimport x` would be parsed as a valid import.
+ i += skipUntil(file, {'\n', '\r', '"', '\''}, i);
  continue;
  }
  i += keywordToParse.size(); // skip "import" or "from"
@@ -256,9 +258,40 @@ kj::Array<kj::String> ArtifactBundler::parsePythonScriptImports(kj::Array<kj::St
  }
  }
  break;
+ }
+ case '"':
+ case '\'': {
+ char quote = file[i];
+ // Detect multi-line string literals `"""` and skip until the corresponding ending `"""`.
+ if (i+2 < file.size() && file[i+1] == quote && file[i+2] == quote) {
+ i += 3; // skip start quotes.
+ // skip until terminating quotes.
+ while (i+2 < file.size() && file[i+1] != quote && file[i+2] != quote) {
+ i += skipUntil(file, {quote}, i);
+ }
+ i += 3; // skip terminating quotes.
+ } else if (i+2 < file.size() && file[i+1] == '\\' && (file[i+2] == '\n' || file[i+2] == '\r')) {
+ // Detect string literal with backslash.
+ i += 3; // skip `"\<NL>`
+ // skip until quote, but ignore `\"`.
+ while (file[i] != quote && file[i-1] != '\\') {
+ i += skipUntil(file, {quote}, i);
+ }
+ i += 1; // skip quote.
+ } else {
+ i += 1; // skip quote.
+ }
+
+ // skip until EOL so that we don't mistakenly parse and capture `"import x`.
+ i += skipUntil(file, {'\n', '\r', '"', '\''}, i);
+ break;
+ }
  default:
- // Skip to the next line.
- i += skipUntil(file, {'\n', '\r'}, i);
+ // Skip to the next line or " or '
+ i += skipUntil(file, {'\n', '\r', '"', '\''}, i);
+ if (file[i] == '"' || file[i] == '\'') {
+ continue; // Allow the quotes to be handled above.
+ }
  if (file[i] != '\0') {
  i += skipChar(file, {'\n', '\r'}, i); // skip newline.
  }