CAY-2975 Mnemonic table aliases in generated SQL

(also required a great deal of refactoring between SQLAppendable and SQLGenerationContext)

Author: andrus

RELEASE-NOTES.txt

@@ -24,6 +24,7 @@ CAY-2970 Tighten deferred value resolution contract on commit
 CAY-2971 Remove extra spaces within SQL parenthesis
 CAY-2972 Fewer parentheses in generated SQL
 CAY-2974 CayenneSqlException with a reference to translated query
+CAY-2975 Mnemonic table aliases in generated SQL
 
 Bug Fixes:
 

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/DefaultSQLAppendable.java

@@ -27,20 +27,12 @@
 public class DefaultSQLAppendable implements SQLAppendable {
 
     final StringBuilder builder;
-    private final SQLGenerationContext context;
     private final QuotingStrategy quotingStrategy;
     private boolean suppressNextSeparator;
 
-    public DefaultSQLAppendable(SQLGenerationContext context) {
+    public DefaultSQLAppendable(QuotingStrategy quotingStrategy) {
         this.builder = new StringBuilder();
-        this.context = context;
-        this.quotingStrategy = resolveQuotes(context);
-    }
-
-    private static QuotingStrategy resolveQuotes(SQLGenerationContext context) {
-        return context == null
-                ? QuotingStrategy.NONE
-                : context.getAdapter().getQuotingStrategy(context.getRootDbEntity());
+        this.quotingStrategy = quotingStrategy == null ? QuotingStrategy.NONE : quotingStrategy;
     }
 
     @Override
@@ -89,11 +81,6 @@ public SQLAppendable suppressNextTokenSeparator() {
         return this;
     }
 
-    @Override
-    public SQLGenerationContext getContext() {
-        return context;
-    }
-
     @Override
     public String getSql() {
         return builder.toString();

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/SQLAppendable.java

@@ -54,7 +54,5 @@ default SQLAppendable append(CharSequence csq, int start, int end) {
 
     SQLAppendable appendQuoted(String str);
 
-    SQLGenerationContext getContext();
-
     String getSql();
 }

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/SQLGenerationContext.java

@@ -23,7 +23,7 @@
 import org.apache.cayenne.dba.DbAdapter;
 import org.apache.cayenne.map.DbEntity;
 
-import java.util.Collection;
+import java.util.List;
 
 /**
  * @since 4.2
@@ -32,7 +32,16 @@ public interface SQLGenerationContext {
 
     DbAdapter getAdapter();
 
-    Collection<PSParameter> getBindings();
+    List<PSParameter<?>> getBindings();
 
     DbEntity getRootDbEntity();
+
+    /**
+     * Returns true if the statement being generated uses a single table, in which case table nodes
+     * and column nodes omit the table alias / prefix for readability (e.g. {@code SELECT NAME FROM
+     * ARTIST} rather than {@code SELECT a.NAME FROM ARTIST a}).
+     *
+     * @since 5.0
+     */
+    boolean isSingleTableSQL();
 }

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/SQLGenerationVisitor.java

@@ -27,14 +27,16 @@
 public class SQLGenerationVisitor implements NodeTreeVisitor {
 
     private final SQLAppendable appendable;
+    private final SQLGenerationContext context;
 
-    public SQLGenerationVisitor(SQLAppendable appendable) {
+    public SQLGenerationVisitor(SQLAppendable appendable, SQLGenerationContext context) {
         this.appendable = appendable;
+        this.context = context;
     }
 
     @Override
     public boolean onNodeStart(Node node) {
-        node.append(appendable);
+        node.append(appendable, context);
         node.appendChildrenStart(appendable);
         return true;
     }

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/sqltree/AliasedNode.java

@@ -21,6 +21,7 @@
 
 import org.apache.cayenne.access.sqlbuilder.NodeTreeVisitor;
 import org.apache.cayenne.access.sqlbuilder.SQLAppendable;
+import org.apache.cayenne.access.sqlbuilder.SQLGenerationContext;
 
 import java.util.Objects;
 
@@ -41,7 +42,7 @@ public Node copy() {
     }
 
     @Override
-    public SQLAppendable append(SQLAppendable buffer) {
+    public SQLAppendable append(SQLAppendable buffer, SQLGenerationContext context) {
         if(skipContent()) {
             buffer.appendTokenSeparator().append(alias);
         }

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/sqltree/BitwiseNotNode.java

@@ -20,14 +20,15 @@
 package org.apache.cayenne.access.sqlbuilder.sqltree;
 
 import org.apache.cayenne.access.sqlbuilder.SQLAppendable;
+import org.apache.cayenne.access.sqlbuilder.SQLGenerationContext;
 
 /**
  * @since 4.2
  */
 public class BitwiseNotNode extends ExpressionNode {
 
     @Override
-    public SQLAppendable append(SQLAppendable buffer) {
+    public SQLAppendable append(SQLAppendable buffer, SQLGenerationContext context) {
         return buffer.append('~');
     }
 

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/sqltree/CaseNode.java

@@ -20,14 +20,15 @@
 package org.apache.cayenne.access.sqlbuilder.sqltree;
 
 import org.apache.cayenne.access.sqlbuilder.SQLAppendable;
+import org.apache.cayenne.access.sqlbuilder.SQLGenerationContext;
 
 /**
  * @since 5.0
  */
 public class CaseNode extends Node {
 
     @Override
-    public SQLAppendable append(SQLAppendable buffer) {
+    public SQLAppendable append(SQLAppendable buffer, SQLGenerationContext context) {
         return buffer.appendTokenSeparator().append("CASE");
     }
 

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/sqltree/ColumnNode.java

@@ -20,6 +20,7 @@
 package org.apache.cayenne.access.sqlbuilder.sqltree;
 
 import org.apache.cayenne.access.sqlbuilder.SQLAppendable;
+import org.apache.cayenne.access.sqlbuilder.SQLGenerationContext;
 import org.apache.cayenne.map.DbAttribute;
 
 import java.util.Objects;
@@ -43,9 +44,10 @@ public ColumnNode(String table, String column, String alias, DbAttribute attribu
     }
 
     @Override
-    public SQLAppendable append(SQLAppendable buffer) {
+    public SQLAppendable append(SQLAppendable buffer, SQLGenerationContext context) {
         buffer.appendTokenSeparator();
-        if (table != null) {
+        // omit the table prefix for a single-table statement
+        if (table != null && (context == null || !context.isSingleTableSQL())) {
             buffer.appendQuoted(table).append('.');
         }
         buffer.appendQuoted(column);

cayenne/src/main/java/org/apache/cayenne/access/sqlbuilder/sqltree/DeleteNode.java

@@ -19,6 +19,7 @@
 package org.apache.cayenne.access.sqlbuilder.sqltree;
 
 import org.apache.cayenne.access.sqlbuilder.SQLAppendable;
+import org.apache.cayenne.access.sqlbuilder.SQLGenerationContext;
 
 /**
  * @since 4.2
@@ -30,7 +31,7 @@ public Node copy() {
     }
 
     @Override
-    public SQLAppendable append(SQLAppendable buffer) {
+    public SQLAppendable append(SQLAppendable buffer, SQLGenerationContext context) {
         return buffer.append("DELETE FROM");
     }
 }