Add support for UTC function

https://docs.oasis-open.org/amqp/filtex/v1.0/csd01/filtex-v1.0-csd01.html#_Toc67929310

Author: ansd

deps/rabbit/src/rabbit_amqp_filter_sql.erl

@@ -76,6 +76,10 @@ eval0({identifier, FieldName}, State) when is_atom(FieldName) ->
           end,
     get_field_value(FieldName, Msg);
 
+%% Function calls
+eval0({function, 'UTC', []}, _Msg) ->
+    os:system_time(millisecond);
+
 %% Logical operators
 %%
 %% Table 3-4 in

deps/rabbit/src/rabbit_amqp_sql_lexer.erl

@@ -22,22 +22,25 @@ REGULAR_ID   = [a-zA-Z][a-zA-Z0-9_]*
 Rules.
 {WHITESPACE}+  : skip_token.
 
-% Logical operators (case insensitive)
+% Logical operators
 AND    : {token, {'AND', TokenLine}}.
 OR     : {token, {'OR', TokenLine}}.
 NOT    : {token, {'NOT', TokenLine}}.
 
-% Special operators (case insensitive)
+% Special operators
 LIKE      : {token, {'LIKE', TokenLine}}.
 IN        : {token, {'IN', TokenLine}}.
 IS        : {token, {'IS', TokenLine}}.
 NULL      : {token, {'NULL', TokenLine}}.
 ESCAPE    : {token, {'ESCAPE', TokenLine}}.
 
-% Boolean literals (case insensitive)
+% Boolean literals
 TRUE     : {token, {boolean, TokenLine, true}}.
 FALSE    : {token, {boolean, TokenLine, false}}.
 
+% Functions
+UTC      : {token, {'UTC', TokenLine}}.
+
 % Comparison operators
 % "The ‘<>’ operator is synonymous to the ‘!=’ operator."
 <>    : {token, {'<>', TokenLine}}.