Support decimal for span used in bin command

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

integ-test/src/test/java/org/opensearch/sql/calcite/remote/CalciteBinCommandIT.java

@@ -1206,4 +1206,12 @@ public void testBinWithEvalCreatedDottedFieldName() throws IOException {
         rows(false, "go", "opentelemetry", 16, 1, "12-14"),
         rows(true, "rust", "opentelemetry", 12, 1, "14-16"));
   }
+
+  @Test
+  public void testBinWithDecimalSpan() throws IOException {
+    JSONObject result =
+        executeQuery("source=events_null | bin cpu_usage span=7.5 | stats count() by cpu_usage");
+    verifySchema(result, schema("count()", "bigint"), schema("cpu_usage", "string"));
+    verifyDataRows(result, rows(3, "37.5-45.0"), rows(2, "45.0-52.5"), rows(1, "52.5-60.0"));
+  }
 }

ppl/src/main/antlr/OpenSearchPPLParser.g4

@@ -270,6 +270,7 @@ timechartParameter
 spanLiteral
    : SPANLENGTH
    | INTEGER_LITERAL
+   | DECIMAL_LITERAL
    ;
 
 evalCommand

ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java

@@ -814,6 +814,8 @@ private List<UnresolvedExpression> multiFieldRelevanceArguments(
   public UnresolvedExpression visitSpanLiteral(OpenSearchPPLParser.SpanLiteralContext ctx) {
     if (ctx.INTEGER_LITERAL() != null) {
       return AstDSL.intLiteral(Integer.parseInt(ctx.INTEGER_LITERAL().getText()));
+    } else if (ctx.DECIMAL_LITERAL() != null) {
+      return AstDSL.decimalLiteral(new BigDecimal(ctx.DECIMAL_LITERAL().getText()));
     } else {
       return AstDSL.stringLiteral(ctx.getText());
     }

ppl/src/test/java/org/opensearch/sql/ppl/parser/AstExpressionBuilderTest.java

@@ -14,6 +14,7 @@
 import static org.opensearch.sql.ast.dsl.AstDSL.allFields;
 import static org.opensearch.sql.ast.dsl.AstDSL.and;
 import static org.opensearch.sql.ast.dsl.AstDSL.argument;
+import static org.opensearch.sql.ast.dsl.AstDSL.bin;
 import static org.opensearch.sql.ast.dsl.AstDSL.booleanLiteral;
 import static org.opensearch.sql.ast.dsl.AstDSL.caseWhen;
 import static org.opensearch.sql.ast.dsl.AstDSL.cast;
@@ -1604,5 +1605,18 @@ public void testVisitSpanLiteral() {
             .limit(10)
             .useOther(true)
             .build());
+
+    // Test span literal with decimal value
+    assertEqual(
+        "source=events_null | bin cpu_usage span=7.5 | stats count() by cpu_usage",
+        agg(
+            bin(
+                relation("events_null"),
+                field("cpu_usage"),
+                argument("span", decimalLiteral(new java.math.BigDecimal("7.5")))),
+            exprList(alias("count()", aggregate("count", allFields()))),
+            emptyList(),
+            exprList(alias("cpu_usage", field("cpu_usage"))),
+            defaultStatsArgs()));
   }
 }