chore: make statement parsing public (marked as InternalApi) (#1690)

Statement parsing is currently done internally in the Connection API do
determine what RPC to execute on the backend. The parsing is however
also very useful to some other applications, specifically PgAdapter,
which can use this to determine what response to send to a PG client.
This makes the parse method and related class and methods public, but
marks them as InternalApi, so they can be used in PgAdapter. This
follows the same pattern that was used to expose certain methods in the
Connection API for the JDBC driver.

Author: olavloite

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

@@ -130,7 +130,8 @@ public static AbstractStatementParser getInstance(Dialect dialect) {
           .parse(Statement.of("RUN BATCH"));
 
   /** The type of statement that has been recognized by the parser. */
-  enum StatementType {
+  @InternalApi
+  public enum StatementType {
     CLIENT_SIDE,
     DDL,
     QUERY,
@@ -139,7 +140,8 @@ enum StatementType {
   }
 
   /** A statement that has been parsed */
-  static class ParsedStatement {
+  @InternalApi
+  public static class ParsedStatement {
     private final StatementType type;
     private final ClientSideStatementImpl clientSideStatement;
     private final Statement statement;
@@ -217,11 +219,18 @@ public boolean equals(Object other) {
           && Objects.equals(this.sqlWithoutComments, o.sqlWithoutComments);
     }
 
-    StatementType getType() {
+    /** Returns the type of statement that was recognized by the parser. */
+    @InternalApi
+    public StatementType getType() {
       return type;
     }
 
-    boolean isQuery() {
+    /**
+     * Returns true if the statement is a query that will return a {@link
+     * com.google.cloud.spanner.ResultSet}.
+     */
+    @InternalApi
+    public boolean isQuery() {
       switch (type) {
         case CLIENT_SIDE:
           return getClientSideStatement().isQuery();
@@ -235,7 +244,12 @@ boolean isQuery() {
       return false;
     }
 
-    boolean isUpdate() {
+    /**
+     * Returns true if the statement is a DML statement or a client side statement that will return
+     * an update count.
+     */
+    @InternalApi
+    public boolean isUpdate() {
       switch (type) {
         case CLIENT_SIDE:
           return getClientSideStatement().isUpdate();
@@ -249,7 +263,9 @@ boolean isUpdate() {
       return false;
     }
 
-    boolean isDdl() {
+    /** Returns true if the statement is a DDL statement. */
+    @InternalApi
+    public boolean isDdl() {
       switch (type) {
         case DDL:
           return true;
@@ -286,7 +302,9 @@ Statement mergeQueryOptions(Statement statement, QueryOptions defaultQueryOption
           .build();
     }
 
-    String getSqlWithoutComments() {
+    /** Returns the SQL statement with all comments removed from the SQL string. */
+    @InternalApi
+    public String getSqlWithoutComments() {
       return sqlWithoutComments;
     }
 
@@ -321,7 +339,8 @@ ClientSideStatement getClientSideStatement() {
    * @param statement The statement to parse.
    * @return the parsed and categorized statement.
    */
-  ParsedStatement parse(Statement statement) {
+  @InternalApi
+  public ParsedStatement parse(Statement statement) {
     return parse(statement, null);
   }