[tracker] libtracker-data: Add support for the STRLEN() builtin function

[Carlos Garnacho <carlosg src gnome org>]

commit 2df69e80588dad1a8d7fd53b2c1fa0ab903ffbba
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Jul 28 20:29:19 2015 +0200

    libtracker-data: Add support for the STRLEN() builtin function
    
    This function is defined in Sparql 1.1 query recommendation,
    http://www.w3.org/TR/sparql11-query/#func-strlen

 src/libtracker-data/tracker-sparql-expression.vala |    6 ++++++
 src/libtracker-data/tracker-sparql-scanner.vala    |    6 ++++++
 2 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql-expression.vala 
b/src/libtracker-data/tracker-sparql-expression.vala
index b655d0f..44dfe30 100644
--- a/src/libtracker-data/tracker-sparql-expression.vala
+++ b/src/libtracker-data/tracker-sparql-expression.vala
@@ -1224,6 +1224,12 @@ class Tracker.Sparql.Expression : Object {
                        var result = translate_function (sql, FN_NS + "upper-case");
                        expect (SparqlTokenType.CLOSE_PARENS);
                        return result;
+               case SparqlTokenType.STRLEN:
+                       next ();
+                       sql.append ("LENGTH(");
+                       type = translate_aggregate_expression (sql);
+                       sql.append (")");
+                       return PropertyType.INTEGER;
                case SparqlTokenType.REGEX:
                        translate_regex (sql);
                        query.no_cache = true;
diff --git a/src/libtracker-data/tracker-sparql-scanner.vala b/src/libtracker-data/tracker-sparql-scanner.vala
index ac2940c..a1454aa 100644
--- a/src/libtracker-data/tracker-sparql-scanner.vala
+++ b/src/libtracker-data/tracker-sparql-scanner.vala
@@ -317,6 +317,10 @@ public class Tracker.SparqlScanner : Object {
                                case 'i':
                                        if (matches (begin, "SILENT")) return SparqlTokenType.SILENT;
                                        break;
+                               case 'T':
+                               case 't':
+                                       if (matches (begin, "STRLEN")) return SparqlTokenType.STRLEN;
+                                       break;
                                }
                                break;
                        }
@@ -981,6 +985,7 @@ public enum Tracker.SparqlTokenType {
        STRING_LITERAL2,
        STRING_LITERAL_LONG1,
        STRING_LITERAL_LONG2,
+       STRLEN,
        SUM,
        TRUE,
        UCASE,
@@ -1081,6 +1086,7 @@ public enum Tracker.SparqlTokenType {
                case STRING_LITERAL2: return "string literal";
                case STRING_LITERAL_LONG1: return "string literal";
                case STRING_LITERAL_LONG2: return "string literal";
+               case STRLEN: return "`STRLEN'";
                case SUM: return "`SUM'";
                case TRUE: return "`true'";
                case UCASE: return "`UCASE'";