[gxml] StreamReader: initial stream mapper implementation

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 9129dc16f44b24209f89fec1118892a858ad327b
Author: Daniel Espinosa <esodan gmail com>
Date:   Mon Jul 22 10:37:18 2019 -0500

    StreamReader: initial stream mapper implementation

 gxml/ParserStream.vala |  10 ---
 gxml/StreamReader.vala | 166 +++++++++++++++++++++++++++++++++++++++++++++++++
 gxml/meson.build       |   1 +
 3 files changed, 167 insertions(+), 10 deletions(-)
---
diff --git a/gxml/ParserStream.vala b/gxml/ParserStream.vala
index 6c07e83..3e1dfad 100644
--- a/gxml/ParserStream.vala
+++ b/gxml/ParserStream.vala
@@ -32,7 +32,6 @@ public class GXml.ParserStream : GLib.Object {
   DomDocument doc;
   Regex reg_name_star_char;
   Regex reg_name;
-  size_t position = -1;
   Gee.ArrayList<ElementBuffered> elements = new Gee.ArrayList<ElementBuffered> ();
 
   public GLib.Cancellable? cancellable { get; set; }
@@ -51,14 +50,12 @@ public class GXml.ParserStream : GLib.Object {
     char buf[2] = {0, 0};
     var dstream = new GLib.DataInputStream (istream);
     buf[0] = (char) dstream.read_byte (cancellable);
-    position++;
     string start = null;
     if (buf[0] != '<') {
       throw new ParserStreamError.INVALID_DOCUMENT_ERROR (_("Invalid document: should start with '<'"));
     }
     start = (string) buf;
     buf[0] = (char) dstream.read_byte (cancellable);
-    position++;
     str += (string) buf;
     if (str == "?") {
       start = null;
@@ -147,7 +144,6 @@ public class GXml.ParserStream : GLib.Object {
   public void skip_spaces (GLib.DataInputStream dstream, out char cur) throws GLib.Error {
     char buf[2] = {0, 0};
     buf[0] = (char) dstream.read_byte (cancellable);
-    position++;
     while (is_space (buf[0])) {
       buf[0] = (char) dstream.read_byte (cancellable);
       position++;
@@ -180,7 +176,6 @@ public class GXml.ParserStream : GLib.Object {
     char buf[2] = {0, 0};
     string str = "";
     buf[0] = (char) dstream.read_byte (cancellable);
-    position++;
     while (buf[0] != quote)) {
       str += (string) buf[0];
       buf[0] = (char) dstream.read_byte (cancellable);
@@ -194,17 +189,14 @@ public class GXml.ParserStream : GLib.Object {
     string val = null;
     read_name (dstream, out cur, out name);
     buf[0] = (char) dstream.read_byte (cancellable);
-    position++;
     if (buf[0] != '=') {
       throw new ParserStreamError.INVALID_DOCUMENT_ERROR (_("Invalid attribute: expected '=' character"));
     }
     char quote = (char) dstream.read_byte (cancellable);
-    position++;
     if (quote != quote1 || quote != quote2) {
       throw new ParserStreamError.INVALID_DOCUMENT_ERROR (_("Invalid attribute: expected quote"));
     }
     buf[0] = (char) dstream.read_byte (cancellable);
-    position++;
     char q = quote1 != '\0' ? quot1 : quote2 != '\0' ? quote2 : '\0';
     if (q == '\0') {
       throw new ParserStreamError.INVALID_DOCUMENT_ERROR (_("Invalid qouting requested for attribute read"));
@@ -237,7 +229,6 @@ public class GXml.ParserStream : GLib.Object {
       }
     }
     buf[0] = (char) dstream.read_byte (cancellable);
-    position++;
     if (buf[0] != '<' && start == null) {
       throw new ParserStreamError.INVALID_DOCUMENT_ERROR (_("Invalid element start tag declaration: expected 
'<'"));
     }
@@ -274,7 +265,6 @@ public class GXml.ParserStream : GLib.Object {
   public void read_element_content (GLib.DataInputStream dstream, GLib.DataOutputStream dostream, string 
node_name) {
     char buf[2] = {0, 0};
     buf[0] = (char) dstream.read_byte (cancellable);
-    position++;
     while (buf[0] != '<') {
       if (!dostream.put_byte (buf[0])) {
         throw new ParserStreamError.MEMORY_ERROR (_("Can't load element's content"));
diff --git a/gxml/StreamReader.vala b/gxml/StreamReader.vala
new file mode 100644
index 0000000..af391da
--- /dev/null
+++ b/gxml/StreamReader.vala
@@ -0,0 +1,166 @@
+/* -*- Mode: vala; indent-tabs-mode: nil; c-basic-offset: 2; tab-width: 2 -*- */
+/* ParserStream.vala
+ *
+ * Copyright (C) 2019  Daniel Espinosa <esodan 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:
+ *      Daniel Espinosa <esodan gmail com>
+ */
+public errordomain GXml.StreamReaderError {
+  INVALID_DOCUMENT_ERROR
+}
+
+
+public class GXml.StreamReader : GLib.Object {
+  public size_t xml_def_pos_start { get; set; }
+  public size_t xml_def_pos_end { get; set; }
+  public size_t doc_type_pos_start { get; set; }
+  public size_t doc_type_pos_end { get; set; }
+  public size_t root_pos_start { get; set; }
+  public size_t root_pos_end { get; set; }
+  public size_t current_pos { get; set; }
+  public DataOutputStream buffer { get; }
+  public DataInputStream stream { get; }
+  public Cancellable? cancellable { get; set; }
+  public bool has_xml_dec { get; set; }
+  public bool has_doc_type_dec { get; set; }
+  public bool has_root { get; set; }
+  public void read () throws GLib.Error {
+    char buf[2] = {0, 0};
+    int64 pos = -1;
+    buf[0] = (char) stream.read_byte (cancellable);
+    if (buf[0] != '<') {
+      throw new StreamReaderError.INVALID_DOCUMENT_ERROR (_("Invalid document: should start with '<'"));
+    }
+    pos = stream.tell ();
+    buf[0] = (char) stream.read_byte (cancellable);
+    if (buf[0] == '?') {
+      buf[0] = (char) stream.read_byte (cancellable);
+      if (buf[0] == 'x') {
+        string xmldef = stream.read_line (null, cancellable);
+        xmldef = "<?"+xmldef;
+        validate_xml_definition ();
+        has_xml_dec = true;
+      } else {
+        stream.seek (-2, SeekType.CUR, cancellable);
+        buf[0] = (char) stream.read_byte (cancellable);
+        read_misc (buf[0]);
+      }
+    }
+    while (!has_root) {
+      buf[0] = (char) stream.read_byte (cancellable);
+      if (buf[0] != '<') {
+        throw new StreamReaderError.INVALID_DOCUMENT_ERROR (_("Invalid document: expected '<' character"));
+      }
+      buf[0] = (char) stream.read_byte (cancellable);
+      if (buf[0] == '!' || buf[0] == '?') {
+        read_misc (buf[0]);
+      } else {
+        has_root = true;
+      }
+    }
+    if (is_space (buf[0])) {
+      throw new StreamReaderError.INVALID_DOCUMENT_ERROR (_("Invalid document: unexpected character"));
+    }
+    read_element ();
+  }
+  public bool read_misc (char c) throws GLib.Error {
+    char buf[2] = {0, 0};
+    if (c == '!') {
+      int64 pos = stream.tell () - 1;
+      buf[0] = (char) stream.read_byte (cancellable);
+      if (buf[0] == 'D') {
+        doc_type_pos_start = (size_t) pos;
+        string doctype = stream.read_upto (">", -1, null, cancellable);
+        doctype = "<!"+doctype+">";
+        buf[0] = (char) stream.read_byte (cancellable);
+        validate_doc_type_definition ();
+        has_doc_type_dec = true;
+        doc_type_pos_end = (size_t) stream.tell ();
+      } else if (c == '-') {
+        buf[0] = (char) stream.read_byte (cancellable);
+        if (buf[0] == '-') {
+          string comment = stream.read_upto ("-->", -1, null, cancellable);
+          comment += "<!--"+comment+"-->";
+          buf[0] = (char) stream.read_byte (cancellable);
+          buf[0] = (char) stream.read_byte (cancellable);
+          buf[0] = (char) stream.read_byte (cancellable);
+        } else {
+          throw new StreamReaderError.INVALID_DOCUMENT_ERROR (_("Invalid document: expected '-' character"));
+        }
+      }
+    } else if (buf[0] == '?') {
+      string pi = stream.read_upto ("?>", -1, null, cancellable);
+      pi += "<?"+pi+"?>";
+      buf[0] = (char) stream.read_byte (cancellable);
+      buf[0] = (char) stream.read_byte (cancellable);
+    }
+    return true;
+  }
+  /**
+   * Reads an element name, attributes and content as string
+   *
+   * Expects a one byte consumed from {@link stream}, because
+   * it seeks back one byte in order to read the element's name.
+   *
+   * Returns: A string representing the current node
+   */
+  public string read_element (bool is_root = true) throws GLib.Error {
+    string str = "";
+    char buf[2] = {0, 0};
+    if (is_root) {
+      root_pos_start = (size_t) (stream.tell () - 1);
+    }
+    stream.seek (-1, SeekType.CUR, cancellable);
+    string name = stream.read_upto (" ", -1, null, cancellable);
+    string atts = stream.read_upto (">", -1, null, cancellable);
+    stream.read_byte (cancellable);
+    str = "<"+name+atts+">";
+    if (is_root) {
+      string content = stream.read_upto ("<", -1, null, cancellable);
+      buf[0] = (char) stream.read_byte (cancellable);
+      str += content;
+      buf[0] = (char) stream.read_byte (cancellable);
+      if (buf[0] == '/') {
+        string closetag = stream.read_upto (">", -1, null, cancellable);
+        buf[0] = (char) stream.read_byte (cancellable);
+        root_pos_end = (size_t) stream.tell ();
+        str += closetag + ">";
+      } else {
+        read_element (false);
+      }
+    } else {
+      string cltag = "</"+name;
+      string content = stream.read_upto (cltag, -1, null, cancellable);
+      str += content;
+      for (int i = 0; i < cltag.data.length; i++) {
+        stream.read_byte (cancellable);
+      }
+      root_pos_end = (size_t) stream.tell ();
+      str += cltag;
+    }
+    return str;
+  }
+  public bool is_space (char c) {
+    return c == 0x20 || c == 0x9 || c == 0xA;
+  }
+  public bool validate_xml_definition () throws GLib.Error {
+    return true;
+  }
+  public bool validate_doc_type_definition () throws GLib.Error {
+    return true;
+  }
+}
diff --git a/gxml/meson.build b/gxml/meson.build
index 49d49cf..5f19bc8 100644
--- a/gxml/meson.build
+++ b/gxml/meson.build
@@ -70,6 +70,7 @@ valasources = files ([
        'Property.vala',
        'Range.vala',
        'SettableTokenList.vala',
+       'StreamReader.vala',
        'StringRef.vala',
        'Text.vala',
        'TokenList.vala',