fix #1. Queries support an order clause and limit clause.

src/parser/parser.go

@@ -88,6 +88,7 @@ type Query struct {
 	Condition     *WhereCondition
 	groupByClause GroupByClause
 	Limit         int
+	Ascending     bool
 }
 
 func (self *Query) GetColumnNames() []*Value {
@@ -250,5 +251,5 @@ func ParseQuery(query string) (*Query, error) {
 		C.close_query(&q)
 		return nil, err
 	}
-	return &Query{q, false, nil, nil, nil, int(q.limit)}, err
+	return &Query{q, false, nil, nil, nil, int(q.limit), q.ascending != 0}, err
 }

src/parser/parser_test.go

@@ -274,16 +274,25 @@ func (self *QueryParserSuite) TestParseWhereClauseParantheses(c *C) {
 	c.Assert(third.Operation, Equals, "<")
 }
 
-func (self *QueryParserSuite) TestParseSelectWithLast(c *C) {
-	q, err := ParseQuery("select value from t last 10;")
-	defer q.Close()
-	c.Assert(err, IsNil)
-	c.Assert(q.Limit, Equals, -10)
-
-	q, err = ParseQuery("select value from t first 10;")
+func (self *QueryParserSuite) TestParseSelectWithOrderByAndLimit(c *C) {
+	q, err := ParseQuery("select value from t order asc limit 10;")
 	defer q.Close()
 	c.Assert(err, IsNil)
 	c.Assert(q.Limit, Equals, 10)
+	c.Assert(q.Ascending, Equals, true)
+
+	q, err = ParseQuery("select value from t order desc;")
+	defer q.Close()
+	c.Assert(err, IsNil)
+	c.Assert(q.Limit, Equals, 0)
+	c.Assert(q.Ascending, Equals, false)
+
+	q, err = ParseQuery("select value from t limit 20;")
+	defer q.Close()
+	c.Assert(err, IsNil)
+	c.Assert(q.Limit, Equals, 20)
+	// ascending is the default
+	c.Assert(q.Ascending, Equals, true)
 }
 
 func (self *QueryParserSuite) TestParseFromWithNestedFunctions2(c *C) {

src/parser/query.lex

@@ -27,6 +27,10 @@ last                      { return LAST; }
 from                      { return FROM; }
 where                     { return WHERE; }
 select                    { return SELECT; }
+limit                     { return LIMIT; }
+order                     { return ORDER; }
+asc                       { return ASC; }
+desc                      { return DESC; }
 group                     { return GROUP; }
 by                        { return BY; }
 "("                       { yylval->character = *yytext; return *yytext; }

src/parser/query.yacc

@@ -25,6 +25,10 @@ expression *create_expression(expression *left, char op, expression *right) {
   expression*           expression;
   value_array*          value_array;
   value*                v;
+  struct {
+    int limit;
+    char ascending;
+  } limit_and_order;
 }
 
 // debugging
@@ -41,7 +45,7 @@ expression *create_expression(expression *left, char op, expression *right) {
 %lex-param   {void *scanner}
 
 // define types of tokens (terminals)
-%token          SELECT FROM WHERE EQUAL GROUP BY FIRST LAST
+%token          SELECT FROM WHERE EQUAL GROUP BY FIRST LAST LIMIT ORDER ASC DESC
 %token <string> STRING_VALUE INT_VALUE NAME REGEX_OP REGEX_STRING
 
 // define the precendence of these operators
@@ -63,7 +67,9 @@ expression *create_expression(expression *left, char op, expression *right) {
 %type <v>               FUNCTION_CALL
 %type <expression>      EXPRESSION
 %type <value_array>     GROUP_BY_CLAUSE
-%type <integer>         LIMIT
+%type <integer>         LIMIT_CLAUSE
+%type <character>       ORDER_CLAUSE
+%type <limit_and_order> LIMIT_AND_ORDER_CLAUSES
 
 // the initial token
 %start                  QUERY
@@ -78,34 +84,58 @@ expression *create_expression(expression *left, char op, expression *right) {
 // grammar
 %%
 QUERY:
-        SELECT COLUMN_NAMES FROM_CLAUSE GROUP_BY_CLAUSE WHERE_CLAUSE LIMIT ';'
+        SELECT COLUMN_NAMES FROM_CLAUSE GROUP_BY_CLAUSE WHERE_CLAUSE LIMIT_AND_ORDER_CLAUSES ';'
         {
           q->c = $2;
           q->f = $3;
           q->group_by = $4;
           q->where_condition = $5;
-          q->limit = $6;
+          q->limit = $6.limit;
+          q->ascending = $6.ascending;
         }
         |
-        SELECT COLUMN_NAMES FROM_CLAUSE WHERE_CLAUSE GROUP_BY_CLAUSE LIMIT ';'
+        SELECT COLUMN_NAMES FROM_CLAUSE WHERE_CLAUSE GROUP_BY_CLAUSE LIMIT_AND_ORDER_CLAUSES ';'
         {
           q->c = $2;
           q->f = $3;
           q->where_condition = $4;
           q->group_by = $5;
-          q->limit = $6;
+          q->limit = $6.limit;
+          q->ascending = $6.ascending;
         }
 
-LIMIT:
-        FIRST INT_VALUE
+LIMIT_AND_ORDER_CLAUSES:
+        ORDER_CLAUSE LIMIT_CLAUSE
         {
-          $$ = atoi($2);
-          free($2);
+          $$.limit = $2;
+          $$.ascending = $1;
         }
         |
-        LAST INT_VALUE
+        LIMIT_CLAUSE ORDER_CLAUSE
         {
-          $$ = -atoi($2);
+          $$.limit = $1;
+          $$.ascending = $2;
+        }
+
+ORDER_CLAUSE:
+        ORDER ASC
+        {
+          $$ = TRUE;
+        }
+        |
+        ORDER DESC
+        {
+          $$ = FALSE;
+        }
+        |
+        {
+          $$ = TRUE;
+        }
+
+LIMIT_CLAUSE:
+        LIMIT INT_VALUE
+        {
+          $$ = atoi($2);
           free($2);
         }
         |

src/parser/query_types.h

@@ -52,6 +52,7 @@ typedef struct {
   condition *where_condition;
   error *error;
   int limit;
+  char ascending;
 } query;
 
 // some funcs for freeing our types