net.html: create html parser module (#6076)

vlib/net/html/data_structures.v

@@ -0,0 +1,88 @@
+module html
+
+#include <limits.h>
+struct Stack {
+	null_element int = C.INT_MIN
+mut:
+	elements     []int
+	size         int = 0
+}
+
+fn (stack Stack) is_null(data int) bool {
+	return data == stack.null_element
+}
+
+fn (stack Stack) is_empty() bool {
+	return stack.size <= 0
+}
+
+fn (stack Stack) peek() int {
+	if !stack.is_empty() {
+		return stack.elements[stack.size - 1]
+	}
+	return stack.null_element
+}
+
+fn (mut stack Stack) pop() int {
+	mut to_return := stack.null_element
+	if !stack.is_empty() {
+		to_return = stack.elements[stack.size - 1]
+		stack.size--
+	}
+	return to_return
+}
+
+fn (mut stack Stack) push(item int) {
+	if stack.elements.len > stack.size {
+		stack.elements[stack.size] = item
+	} else {
+		stack.elements << item
+	}
+	stack.size++
+}
+
+struct BTree {
+mut:
+	all_tags     []Tag
+	node_pointer int = 0
+	childrens    [][]int
+	parents      []int
+}
+
+fn (mut btree BTree) add_children(tag Tag) int {
+	btree.all_tags << tag
+	if btree.all_tags.len > 1 {
+		for btree.childrens.len <= btree.node_pointer {
+			// println("${btree.childrens.len} <= ${btree.node_pointer}")
+			mut temp_array := btree.childrens
+			temp_array << []int{}
+			btree.childrens = temp_array
+		}
+		btree.childrens[btree.node_pointer] << btree.all_tags.len - 1
+		for btree.parents.len < btree.all_tags.len {
+			mut temp_array := btree.parents
+			temp_array << 0
+			btree.parents = temp_array
+		}
+		btree.parents[btree.all_tags.len - 1] = btree.node_pointer
+	}
+	return btree.all_tags.len - 1
+}
+
+fn (btree BTree) get_children() []int {
+	return btree.childrens[btree.node_pointer]
+}
+
+fn (btree BTree) get_parent() int {
+	return btree.parents[btree.node_pointer]
+}
+
+fn (btree BTree) get_stored() Tag {
+	return btree.all_tags[btree.node_pointer]
+}
+
+fn (mut btree BTree) move_pointer(to int) {
+	if to < btree.all_tags.len {
+		btree.node_pointer = to
+	}
+}