chore: allow comments in PG strings (#2604)

Allow comments in PostgreSQL query strings for extracting parameter definitions. The comments need to be preserved, as they could contain query hints.

Author: olavloite

google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/AbstractStatementParser.java

@@ -539,11 +539,10 @@ public static class ParametersInfo {
  * Converts all positional parameters (?) in the given sql string into named parameters. The
  * parameters are named @p1, @p2, etc. This method is used when converting a JDBC statement that
  * uses positional parameters to a Cloud Spanner {@link Statement} instance that requires named
- * parameters. The input SQL string may not contain any comments. There is an exception case if
- * the statement starts with a GSQL comment which forces it to be interpreted as a GoogleSql
- * statement.
+ * parameters. The input SQL string may not contain any comments, except for PostgreSQL-dialect
+ * SQL strings.
  *
- * @param sql The sql string without comments that should be converted
+ * @param sql The sql string that should be converted
  * @return A {@link ParametersInfo} object containing a string with named parameters instead of
  * positional parameters and the number of parameters.
  * @throws SpannerException If the input sql string contains an unclosed string/byte literal.

google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/PostgreSQLStatementParser.java

@@ -184,9 +184,8 @@ ParametersInfo convertPositionalParametersToNamedParametersInternal(char paramCh
  * Note: This is an internal API and breaking changes can be made without prior notice.
  *
  * <p>Returns the PostgreSQL-style query parameters ($1, $2, ...) in the given SQL string. The
- * SQL-string is assumed to not contain any comments. Use {@link #removeCommentsAndTrim(String)}
- * to remove all comments before calling this method. Occurrences of query-parameter like strings
- * inside quoted identifiers or string literals are ignored.
+ * SQL-string is allowed to contain comments. Occurrences of query-parameter like strings inside
+ * quoted identifiers or string literals are ignored.
  *
  * <p>The following example will return a set containing ("$1", "$2"). <code>
  * select col1, col2, "col$4"
@@ -195,7 +194,7 @@ ParametersInfo convertPositionalParametersToNamedParametersInternal(char paramCh
  * and not col3=$1 and col4='$3'
  * </code>
  *
- * @param sql the SQL-string to check for parameters. Must not contain comments.
+ * @param sql the SQL-string to check for parameters.
  * @return A set containing all the parameters in the SQL-string.
  */
  @InternalApi
@@ -233,12 +232,56 @@ private int skip(String sql, int currentIndex, @Nullable StringBuilder result) {
  return skipQuoted(
  sql, currentIndex + dollarTag.length() + 1, currentChar, dollarTag, result);
  }
+ } else if (currentChar == HYPHEN
+ && sql.length() > (currentIndex + 1)
+ && sql.charAt(currentIndex + 1) == HYPHEN) {
+ return skipSingleLineComment(sql, currentIndex, result);
+ } else if (currentChar == SLASH
+ && sql.length() > (currentIndex + 1)
+ && sql.charAt(currentIndex + 1) == ASTERISK) {
+ return skipMultiLineComment(sql, currentIndex, result);
  }
 
  appendIfNotNull(result, currentChar);
  return currentIndex + 1;
  }
 
+ static int skipSingleLineComment(String sql, int currentIndex, @Nullable StringBuilder result) {
+ int endIndex = sql.indexOf('\n', currentIndex + 2);
+ if (endIndex == -1) {
+ endIndex = sql.length();
+ } else {
+ // Include the newline character.
+ endIndex++;
+ }
+ appendIfNotNull(result, sql.substring(currentIndex, endIndex));
+ return endIndex;
+ }
+
+ static int skipMultiLineComment(String sql, int startIndex, @Nullable StringBuilder result) {
+ // Current position is start + '/*'.length().
+ int pos = startIndex + 2;
+ // PostgreSQL allows comments to be nested. That is, the following is allowed:
+ // '/* test /* inner comment */ still a comment */'
+ int level = 1;
+ while (pos < sql.length()) {
+ if (sql.charAt(pos) == SLASH && sql.length() > (pos + 1) && sql.charAt(pos + 1) == ASTERISK) {
+ level++;
+ }
+ if (sql.charAt(pos) == ASTERISK && sql.length() > (pos + 1) && sql.charAt(pos + 1) == SLASH) {
+ level--;
+ if (level == 0) {
+ pos += 2;
+ appendIfNotNull(result, sql.substring(startIndex, pos));
+ return pos;
+ }
+ }
+ pos++;
+ }
+ appendIfNotNull(result, sql.substring(startIndex));
+ return sql.length();
+ }
+
  private int skipQuoted(
  String sql, int startIndex, char startQuote, @Nullable StringBuilder result) {
  return skipQuoted(sql, startIndex, startQuote, null, result);
@@ -285,6 +328,12 @@ private void appendIfNotNull(@Nullable StringBuilder result, char currentChar) {
  }
  }
 
+ private static void appendIfNotNull(@Nullable StringBuilder result, String suffix) {
+ if (result != null) {
+ result.append(suffix);
+ }
+ }
+
  private void appendIfNotNull(
  @Nullable StringBuilder result, char prefix, String tag, char suffix) {
  if (result != null) {