[gxml] Added implementation for CSS Selector

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit e821de2e022698700b9e55421ba2c0ddb6d8cd86
Author: Yannick Inizan <inizan yannick gmail com>
Date:   Tue Sep 5 15:30:52 2017 -0700

    Added implementation for CSS Selector

 gxml/css-selector-parser.vala |  285 +++++++++++++++++++++++++++++++++++++++++
 gxml/meson.build              |    1 +
 2 files changed, 286 insertions(+), 0 deletions(-)
---
diff --git a/gxml/css-selector-parser.vala b/gxml/css-selector-parser.vala
new file mode 100644
index 0000000..484dca7
--- /dev/null
+++ b/gxml/css-selector-parser.vala
@@ -0,0 +1,285 @@
+/* -*- Mode: vala; indent-tabs-mode: nil; c-basic-offset: 0; tab-width: 2 -*- */
+/*
+ *
+ * Copyright (C) 2017  Yannick Inizan <inizan yannick gmail com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *      Yannick Inizan <inizan yannick gmail com>
+ */
+public errordomain GXml.SelectorError {
+       NULL,
+       ATTRIBUTE,
+       INVALID,
+       LENGTH,
+       STRING,
+       TYPE
+}
+
+public enum GXml.SelectorType {
+       CLASS,
+       ID,
+       ALL,
+       ELEMENT,
+       ATTRIBUTE,
+       ATTRIBUTE_EQUAL,
+       ATTRIBUTE_CONTAINS,
+       ATTRIBUTE_SUBSTRING,
+       ATTRIBUTE_START_WITH,
+       ATTRIBUTE_END_WITH,
+       PSEUDO,
+       AND,
+       INSIDE,
+       PARENT,
+       AFTER,
+       BEFORE
+}
+
+public struct GXml.SelectorData {
+       public SelectorType selector_type;
+       public string data;
+       public string value;
+}
+
+public class GXml.SelectorParser : GLib.Object {
+       Gee.ArrayList<SelectorData?> list;
+       
+       construct {
+               list = new Gee.ArrayList<SelectorData?>();
+       }
+       
+       void parse_class (string css, ref int position) {
+               position++;
+               StringBuilder sb = new StringBuilder();
+               unichar u = 0;
+               while (css.get_next_char (ref position, out u) && (u.isalnum() || u == '-'))
+                       sb.append_unichar (u);
+               SelectorData data = { SelectorType.CLASS, sb.str };
+               list.add (data);
+       }
+       
+       void parse_id (string css, ref int position) {
+               position++;
+               StringBuilder sb = new StringBuilder();
+               unichar u = 0;
+               while (css.get_next_char (ref position, out u) && (u.isalnum() || u == '-'))
+                       sb.append_unichar (u);
+               SelectorData data = { SelectorType.ID, sb.str };
+               list.add (data);
+       }
+       
+       void parse_all (string css, ref int position) {
+               position++;
+               SelectorData data = { SelectorType.ALL, "*" };
+               list.add (data);
+       }
+       
+       void parse_element (string css, ref int position) {
+               StringBuilder sb = new StringBuilder();
+               unichar u = 0;
+               while (css.get_next_char (ref position, out u) && (u.isalnum() || u == '-'))
+                       sb.append_unichar (u);
+               SelectorData data = { SelectorType.ELEMENT, sb.str };
+               list.add (data);
+       }
+       
+       void parse_attribute (string css, ref int position) throws GLib.Error {
+               position++;
+               StringBuilder sb = new StringBuilder();
+               unichar u = 0;
+               css.get_next_char (ref position, out u);
+               while (u.isspace())
+                       css.get_next_char (ref position, out u);
+               if (!u.isalnum())
+                       throw new SelectorError.ATTRIBUTE ("invalid attribute character");
+               sb.append_unichar (u);
+               while (css.get_next_char (ref position, out u) && u.isalnum())
+                       sb.append_unichar (u);
+               while (u.isspace())
+                       css.get_next_char (ref position, out u);
+               if (u == ']') {
+                       SelectorData data = { SelectorType.ATTRIBUTE, sb.str };
+                       list.add (data);
+                       return;
+               }
+               if (u == '=') {
+                       StringBuilder sb1 = new StringBuilder();
+                       css.get_next_char (ref position, out u);
+                       while (u.isspace())
+                               css.get_next_char (ref position, out u);
+                       unichar s = 0;
+                       if (u == '"' || u == '\'') {
+                               s = u;
+                               css.get_next_char (ref position, out u);
+                       }
+                       if (!u.isalnum())
+                               throw new SelectorError.ATTRIBUTE ("invalid attribute selector character");
+                       sb1.append_unichar (u);
+                       while (css.get_next_char (ref position, out u) && (u.isalnum() || u.isspace()))
+                               sb1.append_unichar (u);
+                       if (s != 0) {
+                               if (u != s)
+                                       throw new SelectorError.STRING ("invalid end of attribute value");
+                               css.get_next_char (ref position, out u);
+                       }
+                       while (u.isspace())
+                               css.get_next_char (ref position, out u);
+                       if (u != ']')
+                               throw new SelectorError.ATTRIBUTE ("invalid end of attribute selector");
+                       SelectorData data = {
+                               SelectorType.ATTRIBUTE_EQUAL,
+                               sb.str,
+                               sb1.str
+                       };
+                       if (s == 0)
+                               data.value = sb1.str.strip();
+                       list.add (data);
+                       return;
+               }
+               StringBuilder sb1 = new StringBuilder();
+               SelectorData data = { SelectorType.ATTRIBUTE, sb.str, "" };
+               if (u == '~')
+                       data.selector_type = SelectorType.ATTRIBUTE_CONTAINS;
+               else if (u == '*')
+                       data.selector_type = SelectorType.ATTRIBUTE_SUBSTRING;
+               else if (u == '|' || u == '^')
+                       data.selector_type = SelectorType.ATTRIBUTE_START_WITH;
+               else if (u == '$')
+                       data.selector_type = SelectorType.ATTRIBUTE_END_WITH;
+               else
+                       throw new SelectorError.ATTRIBUTE ("invalid attribute selector character");
+               css.get_next_char (ref position, out u);
+               if (u != '=')
+                       throw new SelectorError.ATTRIBUTE ("invalid attribute selector character : can't find 
'=' character");
+               css.get_next_char (ref position, out u);
+               while (u.isspace())
+                       css.get_next_char (ref position, out u);
+               unichar s = 0;
+               if (u == '"' || u == '\'') {
+                       s = u;
+                       css.get_next_char (ref position, out u);
+               }
+               if (!u.isalnum())
+                       throw new SelectorError.ATTRIBUTE ("invalid attribute selector character 2 
(%s)".printf (u.to_string()));
+               sb1.append_unichar (u);
+               while (css.get_next_char (ref position, out u) && (u.isalnum() || u.isspace()))
+                       sb1.append_unichar (u);
+               if (s != 0) {
+                       if (u != s)
+                               throw new SelectorError.STRING ("invalid end of attribute value");
+                       css.get_next_char (ref position, out u);
+               }
+               while (u.isspace())
+                       css.get_next_char (ref position, out u);
+               if (u != ']')
+                       throw new SelectorError.ATTRIBUTE ("invalid end of attribute selector");
+               if (s == 0)
+                       data.value = sb1.str.strip();
+               else
+                       data.value = sb1.str;
+               list.add (data);
+       }
+       
+       void parse_pseudo (string css, ref int position) throws GLib.Error {
+               position++;
+               StringBuilder sb = new StringBuilder();
+               unichar u = 0;
+               while (css.get_next_char (ref position, out u) && (u.isalnum() || u == '-' || u == ':'))
+                       sb.append_unichar (u);
+               string[] valid_selectors = {
+                       "checked",
+                       "disabled",
+                       "empty",
+                       "enable",
+                       "first-child",
+                       ":first-letter",
+                       ":first-line",
+                       "first-of-type",
+                       "last-child",
+                       "last-of-type"
+               };
+               if (!(sb.str in valid_selectors))
+                       throw new SelectorError.INVALID ("invalid pseudo class selector");
+               SelectorData data = { SelectorType.PSEUDO, sb.str };
+               list.add (data);
+       }
+       
+       public void parse (string query) throws GLib.Error {
+               string css = query.strip();
+               if (css.length == 0)
+                       throw new SelectorError.LENGTH ("invalid string length.");
+               bool space = false;
+               int position = 0;
+               while (position < css.length) {
+                       print ("position : %d (%c)\n", position, css[position]);
+                       if (css[position] == '.')
+                               parse_class (css, ref position);
+                       else if (css[position] == '#')
+                               parse_id (css, ref position);
+                       else if (css[position] == '*')
+                               parse_all (css, ref position);
+                       else if (css[position] == '[')
+                               parse_attribute (css, ref position);
+                       else if (css[position] == ':')
+                               parse_pseudo (css, ref position);
+                       else if (css[position].isalnum())
+                               parse_element (css, ref position);
+                       else if (css[position] == ',') {
+                               position++;
+                               SelectorData data = { SelectorType.AND, "," };
+                               list.add (data);
+                       }
+                       else if (css[position] == '+') {
+                               position++;
+                               SelectorData data = { SelectorType.AFTER, "+" };
+                               list.add (data);
+                       }
+                       else if (css[position] == '~') {
+                               position++;
+                               SelectorData data = { SelectorType.BEFORE, "~" };
+                               list.add (data);
+                       }
+                       else if (css[position] == '>') {
+                               position++;
+                               SelectorData data = { SelectorType.PARENT, ">" };
+                               list.add (data);
+                       }
+                       else if (css[position].isspace()) {
+                               unichar u = 0;
+                               css.get_next_char (ref position, out u);
+                               while (u.isspace())
+                                       css.get_next_char (ref position, out u);
+                               position--;
+                               if (list.size > 0 && list[list.size - 1].selector_type != SelectorType.AND && 
list[list.size - 1].selector_type != SelectorType.PARENT
+                                       && list[list.size - 1].selector_type != SelectorType.BEFORE && 
list[list.size - 1].selector_type != SelectorType.AFTER)
+                               {
+                                       SelectorData data = { SelectorType.INSIDE, " " };
+                                       list.add (data);
+                               }
+                       }
+                       else
+                               throw new SelectorError.TYPE ("invalid '%c' character.".printf 
(css[position]));
+               }
+               
+               foreach (var data in list)
+                       print ("%s\n", data.selector_type.to_string());
+       }
+
+       public Gee.List<SelectorData?> selectors {
+               get {
+                       return list;
+               }
+       }
+}
diff --git a/gxml/meson.build b/gxml/meson.build
index 5a5a29c..cc89273 100644
--- a/gxml/meson.build
+++ b/gxml/meson.build
@@ -37,6 +37,7 @@ configure_file(output : 'config.h',
 
 
 valasources = files ([
+        'css-selector-parser.vala',
        'Attribute.vala',
        'CDATA.vala',
        'Character.vala',