feat: add function expression support to JDQL grammar and parser

CHANGELOG.adoc

@@ -25,6 +25,7 @@ and this project adheres to https://semver.org/spec/v2.0.0.html[Semantic Version
 
 === Added
 
+- Add support for scalar function expressions (UPPER, LOWER, LEFT, RIGHT, LENGTH, ABS) in JDQL string queries
 - Include support to Restriction interface
 - Include support to record projector
 - Include Is annotation support to the Repository

jnosql-communication/jnosql-communication-query/antlr4/org/eclipse/jnosql/query/grammar/data/JDQL.g4

@@ -68,12 +68,7 @@ primary_expression
     ;
 
 function_expression
-    : ('abs(' | 'ABS(') scalar_expression ')'
-    | ('length(' | 'LENGTH(') scalar_expression ')'
-    | ('lower(' | 'LOWER(') scalar_expression ')'
-    | ('upper(' | 'UPPER(') scalar_expression ')'
-    | ('left(' | 'LEFT(') scalar_expression ',' scalar_expression ')'
-    | ('right(' | 'RIGHT(') scalar_expression ',' scalar_expression ')'
+    : (ABS | LENGTH | LOWER | UPPER | LEFT | RIGHT) '(' scalar_expression (',' scalar_expression)* ')'
     ;
 
 special_expression
@@ -84,9 +79,11 @@ special_expression
     | FALSE
     ;
 
-state_field_path_expression : IDENTIFIER (DOT IDENTIFIER)* | FULLY_QUALIFIED_IDENTIFIER | FUNCTION_ID;
+state_field_path_expression : identifier (DOT identifier)* | FULLY_QUALIFIED_IDENTIFIER | FUNCTION_ID;
 
-entity_name : IDENTIFIER; // no ambiguity
+identifier : IDENTIFIER | ABS | LENGTH | LOWER | UPPER | LEFT | RIGHT;
+
+entity_name : identifier; // no ambiguity
 
 enum_literal : IDENTIFIER (DOT IDENTIFIER)* | FULLY_QUALIFIED_IDENTIFIER; // ambiguity with state_field_path_expression resolvable semantically
 
@@ -120,6 +117,12 @@ LOCAL_TIME      : [lL][oO][cC][aA][lL] [tT][iI][mM][eE];
 BETWEEN         : [bB][eE][tT][wW][eE][eE][nN];
 LIKE            : [lL][iI][kK][eE];
 THIS            : [tT][hH][iI][sS];
+ABS             : [aA][bB][sS];
+LENGTH          : [lL][eE][nN][gG][tT][hH];
+LOWER           : [lL][oO][wW][eE][rR];
+UPPER           : [uU][pP][pP][eE][rR];
+LEFT            : [lL][eE][fF][tT];
+RIGHT           : [rR][iI][gG][hH][tT];
 LOCAL           : [lL][oO][cC][aA][lL];
 DATE            : [dD][aA][tT][eE];
 DATETIME        : [dD][aA][tT][eE][tT][iI][mM][eE];

jnosql-communication/jnosql-communication-query/src/main/java/org/eclipse/jnosql/communication/query/data/AbstractWhere.java

@@ -8,6 +8,7 @@
  *  You may elect to redistribute this code under either of these licenses.
  *  Contributors:
  *  Otavio Santana
+ *  Matheus Oliveira
  */
 package org.eclipse.jnosql.communication.query.data;
 
@@ -185,11 +186,6 @@ public void exitIn_expression(JDQLParser.In_expressionContext ctx) {
         and = andCondition;
     }
 
-    @Override
-    public void exitFunction_expression(JDQLParser.Function_expressionContext ctx) {
-        throw new UnsupportedOperationException("The function is not supported in the query: " + ctx.getText());
-    }
-
     private Condition getCondition(JDQLParser.Comparison_expressionContext ctx) {
         var context = ctx.comparison_operator();
         if (context.EQ() != null) {

jnosql-communication/jnosql-communication-query/src/main/java/org/eclipse/jnosql/communication/query/data/DefaultFunction.java

@@ -0,0 +1,36 @@
+/*
+ *  Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *  All rights reserved. This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License v1.0
+ *  and Apache License v2.0 which accompanies this distribution.
+ *  The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
+ *  and the Apache License v2.0 is available at http://www.opensource.org/licenses/apache2.0.php.
+ *  You may elect to redistribute this code under either of these licenses.
+ *  Contributors:
+ *  Matheus Oliveira
+ */
+package org.eclipse.jnosql.communication.query.data;
+
+import org.eclipse.jnosql.communication.query.Function;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+/**
+ * The default implementation of {@link Function}.
+ *
+ * @param name   the function name (e.g., {@code "UPPER"})
+ * @param params the function parameters
+ */
+record DefaultFunction(String name, Object... params) implements Function {
+
+    public DefaultFunction {
+        Objects.requireNonNull(name, "name is required");
+        Objects.requireNonNull(params, "params is required");
+    }
+
+    @Override
+    public String toString() {
+        return name + "(" + Arrays.toString(params) + ")";
+    }
+}

jnosql-communication/jnosql-communication-query/src/main/java/org/eclipse/jnosql/communication/query/data/FunctionQueryValue.java

@@ -0,0 +1,40 @@
+/*
+ *  Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *  All rights reserved. This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License v1.0
+ *  and Apache License v2.0 which accompanies this distribution.
+ *  The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
+ *  and the Apache License v2.0 is available at http://www.opensource.org/licenses/apache2.0.php.
+ *  You may elect to redistribute this code under either of these licenses.
+ *  Contributors:
+ *  Matheus Oliveira
+ */
+package org.eclipse.jnosql.communication.query.data;
+
+import org.eclipse.jnosql.communication.query.Function;
+import org.eclipse.jnosql.communication.query.QueryValue;
+import org.eclipse.jnosql.communication.query.ValueType;
+
+import java.util.Objects;
+
+record FunctionQueryValue(Function function) implements QueryValue<Function> {
+
+    FunctionQueryValue {
+        Objects.requireNonNull(function, "function is required");
+    }
+
+    @Override
+    public Function get() {
+        return function;
+    }
+
+    @Override
+    public ValueType type() {
+        return ValueType.FUNCTION;
+    }
+
+    @Override
+    public String toString() {
+        return function.toString();
+    }
+}

jnosql-communication/jnosql-communication-query/src/main/java/org/eclipse/jnosql/communication/query/data/FunctionType.java

@@ -0,0 +1,64 @@
+/*
+ *  Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *  All rights reserved. This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License v1.0
+ *  and Apache License v2.0 which accompanies this distribution.
+ *  The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
+ *  and the Apache License v2.0 is available at http://www.opensource.org/licenses/apache2.0.php.
+ *  You may elect to redistribute this code under either of these licenses.
+ *  Contributors:
+ *  Matheus Oliveira
+ */
+package org.eclipse.jnosql.communication.query.data;
+
+import org.eclipse.jnosql.query.grammar.data.JDQLParser;
+
+import java.util.function.Predicate;
+
+/**
+ * Maps each JDQL function keyword token to its canonical function name string.
+ *
+ * <p>Use {@link #from(JDQLParser.Function_expressionContext)} to resolve the
+ * function name from a grammar context without if-else chains.</p>
+ */
+enum FunctionType {
+
+    ABS(ctx -> ctx.ABS() != null, 1),
+    LENGTH(ctx -> ctx.LENGTH() != null, 1),
+    LOWER(ctx -> ctx.LOWER() != null, 1),
+    UPPER(ctx -> ctx.UPPER() != null, 1),
+    LEFT(ctx -> ctx.LEFT() != null, 2),
+    RIGHT(ctx -> ctx.RIGHT() != null, 2);
+
+    private final Predicate<JDQLParser.Function_expressionContext> matcher;
+    private final int arity;
+
+    FunctionType(Predicate<JDQLParser.Function_expressionContext> matcher, int arity) {
+        this.matcher = matcher;
+        this.arity = arity;
+    }
+
+    /**
+     * Resolves the canonical function name from a grammar context,
+     * validating that the argument count matches the expected arity.
+     *
+     * @param ctx the function expression context; must not be {@code null}
+     * @return the uppercase function name (e.g., {@code "UPPER"})
+     * @throws UnsupportedOperationException if no known function matches
+     * @throws IllegalArgumentException if the argument count does not match
+     */
+    static String from(JDQLParser.Function_expressionContext ctx) {
+        for (FunctionType type : values()) {
+            if (type.matcher.test(ctx)) {
+                int actual = ctx.scalar_expression().size();
+                if (actual != type.arity) {
+                    throw new IllegalArgumentException(
+                            "Function " + type.name() + " expects " + type.arity
+                                    + " argument(s) but got " + actual);
+                }
+                return type.name();
+            }
+        }
+        throw new UnsupportedOperationException("The function is not supported yet: " + ctx.getText());
+    }
+}

jnosql-communication/jnosql-communication-query/src/main/java/org/eclipse/jnosql/communication/query/data/PrimaryFunction.java

@@ -8,6 +8,7 @@
  *  You may elect to redistribute this code under either of these licenses.
  *  Contributors:
  *  Otavio Santana
+ *  Matheus Oliveira
  */
 package org.eclipse.jnosql.communication.query.data;
 
@@ -53,10 +54,17 @@ public QueryValue<?> apply(JDQLParser.Primary_expressionContext context) {
                 default ->
                         throw new UnsupportedOperationException("The special expression is not supported yet: " + specialExpression);
             };
-        } else if(context.enum_literal() != null) {
+        } else if (context.function_expression() != null) {
+            var functionExpression = context.function_expression();
+            var functionName = FunctionType.from(functionExpression);
+            var params = functionExpression.scalar_expression().stream()
+                    .map(this::processScalar)
+                    .toArray();
+            return new FunctionQueryValue(new DefaultFunction(functionName, params));
+        } else if (context.enum_literal() != null) {
             Enum<?> value = EnumConverter.INSTANCE.apply(context.enum_literal().getText());
             return EnumQueryValue.of(value);
-        } else if(context.state_field_path_expression() != null) {
+        } else if (context.state_field_path_expression() != null) {
             var stateContext = context.state_field_path_expression();
             var stateContextText = stateContext.getText();
             try {
@@ -67,6 +75,16 @@ public QueryValue<?> apply(JDQLParser.Primary_expressionContext context) {
                 return QueryPath.of(stateContextText);
             }
         }
-       throw new UnsupportedOperationException("The primary expression is not supported yet: " + context.getText());
+        throw new UnsupportedOperationException("The primary expression is not supported yet: " + context.getText());
     }
-}
+
+    private Object processScalar(JDQLParser.Scalar_expressionContext context) {
+        if (context.primary_expression() != null) {
+            return apply(context.primary_expression());
+        }
+        if (context.LPAREN() != null && context.scalar_expression().size() == 1) {
+            return processScalar(context.scalar_expression(0));
+        }
+        throw new UnsupportedOperationException("Arithmetic expressions in function arguments are not supported yet: " + context.getText());
+    }
+}