ESQL: TO_ASCII function

docs/reference/query-languages/esql/_snippets/lists/string-functions.md

@@ -1,3 +1,4 @@
+* [`TO_ASCII`](../../functions-operators/string-functions.md#esql-to_ascii)
 * [`BIT_LENGTH`](../../functions-operators/string-functions.md#esql-bit_length)
 * [`BYTE_LENGTH`](../../functions-operators/string-functions.md#esql-byte_length)
 * [`CONCAT`](../../functions-operators/string-functions.md#esql-concat)

docs/reference/query-languages/esql/functions-operators/string-functions.md

@@ -14,6 +14,8 @@ mapped_pages:
 :::{include} ../_snippets/lists/string-functions.md
 :::
 
+:::{include} ../_snippets/functions/layout/to_ascii.md
+:::
 
 :::{include} ../_snippets/functions/layout/bit_length.md
 :::

x-pack/plugin/esql/qa/testFixtures/src/main/resources/string.csv-spec

@@ -2748,3 +2748,14 @@ book_no:keyword | author_encoded:keyword | title_encoded:keyword
 1463            | J.%20R.%20R.%20Tolkien | Realms%20of%20Tolkien%3A%20Images%20of%20Middle-earth
 ;
 
+to_ascii
+required_capability: to_ascii
+// tag::to_ascii[]
+ROW a = "Hello\n\t 世界! 🌍 Café naïve résumé こんにちは 🎉 中文测试 αβγδε 日本語テスト 🚀🔥💧🪨" | EVAL x = TO_ASCII(a) | KEEP x;
+// end::to_ascii[]
+
+// tag::to_ascii-result[]
+x:keyword
+Hello\\n\\t \\u4e16\\u754c! \\U0001f30d Caf\\xe9 na\\xefve r\\xe9sum\\xe9 \\u3053\\u3093\\u306b\\u3061\\u306f \\U0001f389 \\u4e2d\\u6587\\u6d4b\\u8bd5 \\u03b1\\u03b2\\u03b3\\u03b4\\u03b5 \\u65e5\\u672c\\u8a9e\\u30c6\\u30b9\\u30c8 \\U0001f680\\U0001f525\\U0001f4a7\\U0001faa8
+// end::to_ascii-result[]
+;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -1529,7 +1529,12 @@ public enum Cap {
         /**
          * Fix double release in inline stats when LocalRelation is reused
          */
-        INLINE_STATS_DOUBLE_RELEASE_FIX(INLINESTATS_V11.enabled)
+        INLINE_STATS_DOUBLE_RELEASE_FIX(INLINESTATS_V11.enabled),
+
+        /**
+         * Support for string function TO_ASCII
+         */
+        TO_ASCII
 
         ;
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/EsqlFunctionRegistry.java

@@ -197,6 +197,7 @@
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.Split;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.StartsWith;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.Substring;
+import org.elasticsearch.xpack.esql.expression.function.scalar.string.ToAscii;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.ToLower;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.ToUpper;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.Trim;
@@ -397,6 +398,7 @@ private static FunctionDefinition[][] functions() {
                 def(Tau.class, Tau::new, "tau") },
             // string
             new FunctionDefinition[] {
+                def(ToAscii.class, ToAscii::new, "to_ascii"),
                 def(BitLength.class, BitLength::new, "bit_length"),
                 def(ByteLength.class, ByteLength::new, "byte_length"),
                 def(Concat.class, Concat::new, "concat"),

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/ScalarFunctionWritables.java

@@ -53,6 +53,7 @@
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.Split;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.StartsWith;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.Substring;
+import org.elasticsearch.xpack.esql.expression.function.scalar.string.ToAscii;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.ToLower;
 import org.elasticsearch.xpack.esql.expression.function.scalar.string.ToUpper;
 import org.elasticsearch.xpack.esql.expression.predicate.logical.And;
@@ -67,6 +68,7 @@ public class ScalarFunctionWritables {
     public static List<NamedWriteableRegistry.Entry> getNamedWriteables() {
         List<NamedWriteableRegistry.Entry> entries = new ArrayList<>();
         entries.add(And.ENTRY);
+        entries.add(ToAscii.ENTRY);
         entries.add(Atan2.ENTRY);
         entries.add(BitLength.ENTRY);
         entries.add(Case.ENTRY);