feat: make Spanner SQL DDL parsing public

src/main/java/com/google/cloud/solutions/spannerddl/diff/AstTreeUtils.java

@@ -20,6 +20,7 @@
 import com.google.cloud.solutions.spannerddl.parser.Node;
 import com.google.cloud.solutions.spannerddl.parser.SimpleNode;
 import com.google.cloud.solutions.spannerddl.parser.Token;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
@@ -30,6 +31,17 @@
 /** Utility functions for getting and casting Nodes in the parsed AST. */
 public class AstTreeUtils {
 
+  /** Gets (and casts) the first found child of a specific node type. */
+  public static <T> T getOptionalChildByType(Node node, Class<T> type) {
+    for (int i = 0, count = node.jjtGetNumChildren(); i < count; i++) {
+      Node child = node.jjtGetChild(i);
+      if (type.isInstance(child)) {
+        return type.cast(child);
+      }
+    }
+    return null;
+  }
+
   /** Gets (and casts) the first found child of a specific node type. */
   public static <T> T getOptionalChildByType(Node[] children, Class<T> type) {
     for (Node child : children) {
@@ -40,6 +52,18 @@ public static <T> T getOptionalChildByType(Node[] children, Class<T> type) {
     return null;
   }
 
+  /**
+   * Gets (and casts) the first found child of a specific node type, throwing an exception if it
+   * does not exist.
+   */
+  public static <T> T getChildByType(Node node, Class<T> type) {
+    T child = getOptionalChildByType(node, type);
+    if (child == null) {
+      throw new IllegalArgumentException("Cannot find child of type " + type.getName());
+    }
+    return child;
+  }
+
   /**
    * Gets (and casts) the first found child of a specific node type, throwing an exception if it
    * does not exist.
@@ -64,6 +88,19 @@ public static boolean isReservedWord(String word) {
     return reservedWords.contains(word);
   }
 
+  /**
+   * Ensures that the passed Node children are of a specific node type, and returns a List with the
+   * specific type.
+   */
+  public static <T> List<T> getChildrenAssertType(Node node, Class<T> type) {
+    List<T> list = new ArrayList<>();
+    for (int i = 0, count = node.jjtGetNumChildren(); i < count; i++) {
+      Node child = node.jjtGetChild(i);
+      list.add(type.cast(child));
+    }
+    return list;
+  }
+
   /**
    * Ensures that the passed array of Nodes is of a specific node type, and returns a List with the
    * specific type.

src/main/java/com/google/cloud/solutions/spannerddl/diff/DatabaseDefinition.java

@@ -46,7 +46,13 @@
  */
 @AutoValue
 public abstract class DatabaseDefinition {
-  static DatabaseDefinition create(List<ASTddl_statement> statements) {
+  /**
+   * Create a database definition from the list of parsed DDL statements.
+   *
+   * @param statements List of parsed DDL statements
+   * @return DatabaseDefinition instance
+   */
+  public static DatabaseDefinition create(List<ASTddl_statement> statements) {
     // Use LinkedHashMap to preserve creation order in original DDL.
     LinkedHashMap<String, ASTcreate_table_statement> tablesInCreationOrder = new LinkedHashMap<>();
     LinkedHashMap<String, ASTcreate_index_statement> indexes = new LinkedHashMap<>();

src/main/java/com/google/cloud/solutions/spannerddl/diff/DdlDiff.java

@@ -699,8 +699,14 @@ private static String getDatabaseNameFromAlterDatabase(List<ASTddl_statement> st
     }
   }
 
-  @VisibleForTesting
-  static List<ASTddl_statement> parseDdl(String original) throws DdlDiffException {
+  /**
+   * Parses the Cloud Spanner Schema (DDL) string to a list of AST DDL statements.
+   *
+   * @param original DDL to parse
+   * @return List of parsed DDL statements
+   * @throws DdlDiffException if there is an error in parsing the DDL
+   */
+  public static List<ASTddl_statement> parseDdl(String original) throws DdlDiffException {
     // Remove "--" comments and split by ";"
     List<String> statements = Splitter.on(';').splitToList(original.replaceAll("--.*(\n|$)", ""));
     ArrayList<ASTddl_statement> ddlStatements = new ArrayList<>(statements.size());