Add Interval Literal (#190)

This PR adds SQL date intervals, i.e., supports statements such the following:
 ```SQL
 SELECT * FROM t 
    WHERE t.date BETWEEN '2021-01-01' AND DATE '2021-01-01' + 30 DAYS
```
This is achieved by a new type of literal/`Expr`, with type `kExpressionLiteralInterval`. It is returned as second operand of the binary plus (or minus, respectivley) expression, where the start date ist the first one. Only checks if duration is a positive integer and the time unit is any of second(s), minute(s), hour(s), day(s), month(s), year(s). Any further sanity checks are in response of the consuming system.

closes #184 
closes #178

Author: dey4ss

src/parser/bison_parser.cpp

@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 3.7.6.  */
+/* A Bison parser, made by GNU Bison 3.7.5.  */
 
 /* Bison interface for Yacc-like parsers in C
 
@@ -16,7 +16,7 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* As a special exception, you may create a larger work that contains
    part or all of the Bison parser skeleton and distribute that work
@@ -223,20 +223,27 @@ extern int hsql_debug;
     SQL_DAY = 390,                 /* DAY  */
     SQL_MONTH = 391,               /* MONTH  */
     SQL_YEAR = 392,                /* YEAR  */
-    SQL_TRUE = 393,                /* TRUE  */
-    SQL_FALSE = 394,               /* FALSE  */
-    SQL_TRANSACTION = 395,         /* TRANSACTION  */
-    SQL_BEGIN = 396,               /* BEGIN  */
-    SQL_COMMIT = 397,              /* COMMIT  */
-    SQL_ROLLBACK = 398,            /* ROLLBACK  */
-    SQL_EQUALS = 399,              /* EQUALS  */
-    SQL_NOTEQUALS = 400,           /* NOTEQUALS  */
-    SQL_LESS = 401,                /* LESS  */
-    SQL_GREATER = 402,             /* GREATER  */
-    SQL_LESSEQ = 403,              /* LESSEQ  */
-    SQL_GREATEREQ = 404,           /* GREATEREQ  */
-    SQL_NOTNULL = 405,             /* NOTNULL  */
-    SQL_UMINUS = 406               /* UMINUS  */
+    SQL_SECONDS = 393,             /* SECONDS  */
+    SQL_MINUTES = 394,             /* MINUTES  */
+    SQL_HOURS = 395,               /* HOURS  */
+    SQL_DAYS = 396,                /* DAYS  */
+    SQL_MONTHS = 397,              /* MONTHS  */
+    SQL_YEARS = 398,               /* YEARS  */
+    SQL_INTERVAL = 399,            /* INTERVAL  */
+    SQL_TRUE = 400,                /* TRUE  */
+    SQL_FALSE = 401,               /* FALSE  */
+    SQL_TRANSACTION = 402,         /* TRANSACTION  */
+    SQL_BEGIN = 403,               /* BEGIN  */
+    SQL_COMMIT = 404,              /* COMMIT  */
+    SQL_ROLLBACK = 405,            /* ROLLBACK  */
+    SQL_EQUALS = 406,              /* EQUALS  */
+    SQL_NOTEQUALS = 407,           /* NOTEQUALS  */
+    SQL_LESS = 408,                /* LESS  */
+    SQL_GREATER = 409,             /* GREATER  */
+    SQL_LESSEQ = 410,              /* LESSEQ  */
+    SQL_GREATEREQ = 411,           /* GREATEREQ  */
+    SQL_NOTNULL = 412,             /* NOTNULL  */
+    SQL_UMINUS = 413               /* UMINUS  */
   };
   typedef enum hsql_tokentype hsql_token_kind_t;
 #endif
@@ -293,7 +300,7 @@ union HSQL_STYPE
 	std::vector<hsql::OrderDescription*>* order_vec;
 	std::vector<hsql::WithDescription*>* with_description_vec;
 
-#line 297 "bison_parser.h"
+#line 304 "bison_parser.h"
 
 };
 typedef union HSQL_STYPE HSQL_STYPE;

src/parser/bison_parser.h

@@ -181,6 +181,7 @@ int yyerror(YYLTYPE* llocp, SQLParserResult* result, yyscan_t scanner, const cha
 %token VIEW WHEN WITH ADD ALL AND ASC END FOR INT KEY
 %token NOT OFF SET TOP AS BY IF IN IS OF ON OR TO
 %token ARRAY CONCAT ILIKE SECOND MINUTE HOUR DAY MONTH YEAR
+%token SECONDS MINUTES HOURS DAYS MONTHS YEARS INTERVAL
 %token TRUE FALSE
 %token TRANSACTION BEGIN COMMIT ROLLBACK
 
@@ -209,13 +210,13 @@ int yyerror(YYLTYPE* llocp, SQLParserResult* result, yyscan_t scanner, const cha
 %type <table>		    join_clause table_ref_name_no_alias
 %type <expr> 		    expr operand scalar_expr unary_expr binary_expr logic_expr exists_expr extract_expr cast_expr
 %type <expr>		    function_expr between_expr expr_alias param_expr
-%type <expr> 		    column_name literal int_literal num_literal string_literal bool_literal date_literal
+%type <expr> 		    column_name literal int_literal num_literal string_literal bool_literal date_literal interval_literal
 %type <expr> 		    comp_expr opt_where join_condition opt_having case_expr case_list in_expr hint
 %type <expr> 		    array_expr array_index null_literal
 %type <limit>		    opt_limit opt_top
 %type <order>		    order_desc
 %type <order_type>	    opt_order_type
-%type <datetime_field>	datetime_field
+%type <datetime_field>	datetime_field datetime_field_plural duration_field
 %type <column_t>	    column_def
 %type <column_type_t>   column_type
 %type <update_t>	    update_clause
@@ -1007,6 +1008,20 @@ datetime_field:
     |   YEAR { $$ = kDatetimeYear; }
     ;
 
+datetime_field_plural:
+        SECONDS { $$ = kDatetimeSecond; }
+    |   MINUTES { $$ = kDatetimeMinute; }
+    |   HOURS { $$ = kDatetimeHour; }
+    |   DAYS { $$ = kDatetimeDay; }
+    |   MONTHS { $$ = kDatetimeMonth; }
+    |   YEARS { $$ = kDatetimeYear; }
+    ;
+
+duration_field:
+		datetime_field
+	|	datetime_field_plural
+	;
+
 array_expr:
 	  	ARRAY '[' expr_list ']' { $$ = Expr::makeArray($3); }
 	;
@@ -1032,6 +1047,7 @@ literal:
 	|	num_literal
 	|	null_literal
 	|	date_literal
+	|	interval_literal
 	|	param_expr
 	;
 
@@ -1054,7 +1070,7 @@ int_literal:
 	;
 
 null_literal:
-	    	NULL { $$ = Expr::makeNullLiteral(); }
+		NULL { $$ = Expr::makeNullLiteral(); }
 	;
 
 date_literal:
@@ -1070,6 +1086,52 @@ date_literal:
 		}
 	;
 
+interval_literal:
+		int_literal duration_field { $$ = Expr::makeIntervalLiteral($1->ival, $2); delete $1; }
+	|   INTERVAL STRING datetime_field {
+			int duration{0}, chars_parsed{0};
+			// If the whole string is parsed, chars_parsed points to the terminating null byte after the last character
+			if (sscanf($2, "%d%n", &duration, &chars_parsed) != 1 || $2[chars_parsed] != 0) {
+				free($2);
+				yyerror(&yyloc, result, scanner, "Found incorrect interval format. Expected format: INTEGER");
+				YYERROR;
+			}
+			free($2);
+			$$ = Expr::makeIntervalLiteral(duration, $3);
+		}
+	|   INTERVAL STRING {
+			int duration{0}, chars_parsed{0};
+			// 'seconds' and 'minutes' are the longest accepted interval qualifiers (7 chars) + null byte
+			char unit_string[8];
+			// If the whole string is parsed, chars_parsed points to the terminating null byte after the last character
+			if (sscanf($2, "%d %7s%n", &duration, unit_string, &chars_parsed) != 2 || $2[chars_parsed] != 0) {
+				free($2);
+				yyerror(&yyloc, result, scanner, "Found incorrect interval format. Expected format: INTEGER INTERVAL_QUALIIFIER");
+				YYERROR;
+			}
+			free($2);
+
+			DatetimeField unit;
+			if (strcasecmp(unit_string, "second") == 0 || strcasecmp(unit_string, "seconds") == 0) {
+				unit = kDatetimeSecond;
+			} else if (strcasecmp(unit_string, "minute") == 0 || strcasecmp(unit_string, "minutes") == 0) {
+				unit = kDatetimeMinute;
+			} else if (strcasecmp(unit_string, "hour") == 0 || strcasecmp(unit_string, "hours") == 0) {
+				unit = kDatetimeHour;
+			} else if (strcasecmp(unit_string, "day") == 0 || strcasecmp(unit_string, "days") == 0) {
+				unit = kDatetimeDay;
+			} else if (strcasecmp(unit_string, "month") == 0 || strcasecmp(unit_string, "months") == 0) {
+				unit = kDatetimeMonth;
+			} else if (strcasecmp(unit_string, "year") == 0 || strcasecmp(unit_string, "years") == 0) {
+				unit = kDatetimeYear;
+			} else {
+				yyerror(&yyloc, result, scanner, "Interval qualifier is unknown.");
+				YYERROR;
+			}
+			$$ = Expr::makeIntervalLiteral(duration, unit);
+		}
+	;
+
 param_expr:
 		'?' {
 			$$ = Expr::makeParameter(yylloc.total_column);