From ce24e1d22d120e6613f3cd1e04d81135f3d048c9 Mon Sep 17 00:00:00 2001
From: Ricardo Markiewicz <rmarkie@fi.uba.ar>
Date: Mon, 24 Oct 2005 20:48:50 +0000
Subject: [PATCH] Abreviado de Claves Variables.

---
 src/btree.cpp          | 35 +++++++++++++++++++++++-
 src/btree.h            |  4 +++
 src/btree_data.cpp     | 16 +++++++++++
 src/btree_data.h       |  3 +++
 src/clave_variable.cpp | 61 ++++++++++++++++++++++++++++++++++++++++++
 src/clave_variable.h   |  6 ++++-
 6 files changed, 123 insertions(+), 2 deletions(-)

diff --git a/src/btree.cpp b/src/btree.cpp
index c0e72a3..8747177 100644
--- a/src/btree.cpp
+++ b/src/btree.cpp
@@ -990,11 +990,44 @@ std::list<BTreeData *> BTree::ReadKeys (uchar *node, BTreeNodeHeader &node_heade
 		keys.push_back (data);
 	}
 
+	DeAbrevKey (keys);
 	return keys;
 }
 
+void BTree::AbrevKey (std::list<BTreeData *> &lst)
+{
+	/* Claves Fijas No se abrevian */
+	if (key_type == KEY_FIXED) return;
+
+	BTreeData *primera = NULL;
+	std::list<BTreeData *>::iterator it = lst.begin ();
+
+	while (it != lst.end ()) {
+		if ((*it)->Abrev (primera) == false)
+			primera = (*it);
+		it++;
+	}
+}
+
+void BTree::DeAbrevKey (std::list<BTreeData *> &lst)
+{
+	/* Claves Fijas No se abrevian */
+	if (key_type == KEY_FIXED) return;
+
+	BTreeData *primera = NULL;
+	std::list<BTreeData *>::iterator it = lst.begin ();
+
+	while (it != lst.end ()) {
+		if ((*it)->DesAbrev (primera) == false)
+			primera = (*it);
+		it++;
+	}
+}
+
 void BTree::WriteKeys (uchar *node, BTreeNodeHeader &node_header, std::list<BTreeData *> &keys)
 {
+	AbrevKey (keys);
+
 	std::list<BTreeData *>::iterator it = keys.begin ();
 
 	node += sizeof (BTreeNodeHeader);
@@ -1016,7 +1049,7 @@ void BTree::WriteKeys (uchar *node, BTreeNodeHeader &node_header, std::list<BTre
 		it++;
 	}
 
-	/* TODO : incrementar node_header.item_count aca o fuera de este metodo? */
+	DeAbrevKey (keys);
 }
 		
 void BTree::PrintNode (uint num)
diff --git a/src/btree.h b/src/btree.h
index 61fbb8c..f888eea 100644
--- a/src/btree.h
+++ b/src/btree.h
@@ -175,6 +175,10 @@ class BTree {
 		void WriteKeys (uchar *node, BTreeNodeHeader &node_header, std::list<BTreeData *> &keys);
 		void DeleteKeys (std::list<BTreeData *> &keys);
 
+		/* Abreviacion de Claves */
+		void AbrevKey (std::list<BTreeData *> &lst);
+		void DeAbrevKey (std::list<BTreeData *> &lst);
+
 		std::string filename;
 		BTreeFileHeader header;
 		int key_type;
diff --git a/src/btree_data.cpp b/src/btree_data.cpp
index bc0ce93..bf92909 100644
--- a/src/btree_data.cpp
+++ b/src/btree_data.cpp
@@ -63,6 +63,22 @@ bool BTreeData::operator == (const BTreeData &data) const
 	return (*clave) == (*(data.clave));
 }
 
+bool BTreeData::Abrev (BTreeData *anterior)
+{
+	if (anterior == NULL) return false;
+
+	ClaveVariable *c = (ClaveVariable *)clave;
+	return c->Abrev (dynamic_cast<ClaveVariable *>(anterior->getClave ()));
+}
+
+bool BTreeData::DesAbrev (BTreeData *anterior)
+{
+	if (anterior == NULL) return false;
+
+	ClaveVariable *c = (ClaveVariable *)clave;
+	return c->DesAbrev (dynamic_cast<ClaveVariable *>(anterior->getClave ()));
+}
+
 BTreeLeafData::BTreeLeafData (uchar *node, int key_type)
 {
 	if (key_type == BTree::KEY_FIXED)
diff --git a/src/btree_data.h b/src/btree_data.h
index db40598..027c595 100644
--- a/src/btree_data.h
+++ b/src/btree_data.h
@@ -53,6 +53,9 @@ class BTreeData {
 		/** Setea el hijo apuntado */
 		void setChild (uint c) { hijo = c; }
 
+		bool Abrev (BTreeData *anterior);
+		bool DesAbrev (BTreeData *anterior);
+
 		bool operator < (const BTreeData &data) const;
 		bool operator == (const BTreeData &data) const;
 		virtual operator std::string () const {
diff --git a/src/clave_variable.cpp b/src/clave_variable.cpp
index c4fd1f1..47d81ba 100644
--- a/src/clave_variable.cpp
+++ b/src/clave_variable.cpp
@@ -52,3 +52,64 @@ bool ClaveVariable::operator == (const Clave &c) const
 	return data == ((ClaveVariable&)c).data;
 }
 
+bool ClaveVariable::Abrev (ClaveVariable *c)
+{
+	if (c == NULL) return false;
+	int iguales = 0;
+	std::string resto;
+
+	resto = abreviar (c->data, data, iguales);
+
+	/* No hago nada si solo machea un caracter */
+	if (iguales < 2) return false;
+
+	std::stringstream ss;
+	ss << iguales;
+	ss << "|";
+	ss << resto;
+	data = ss.str ();
+
+	return true;
+}
+
+bool ClaveVariable::DesAbrev (ClaveVariable *c)
+{
+	if (c == NULL) return false;
+
+	int pos = data.find ("|");
+
+	/* No esta abreviada! */
+	if (pos <= 0) return false;
+
+	std::string siguales = data.substr (0, pos);
+	std::cout << siguales << std::endl;
+	int iguales = atoi (siguales.c_str ());
+
+	std::string primera_parte = c->data.substr (0, iguales);
+	std::string segunda_parte = data.substr (pos+1, data.size () - pos - 1);
+
+	data = primera_parte + segunda_parte;
+
+	return true;
+}
+
+std::string ClaveVariable::abreviar(std::string &p, std::string &a, int &iguales)
+{
+	char *primera = (char *)p.c_str ();
+	char *actual = (char *)a.c_str ();
+
+	iguales = 0;
+	while (((*primera) != '\0') && ((*actual) != '\0')) {
+		if ((*primera) == (*actual)) {
+			primera++;
+			actual++;
+			iguales++;
+		} else {
+			/* No coinciden mas! */
+			break;
+		}
+	}
+
+	return std::string (actual);
+}
+
diff --git a/src/clave_variable.h b/src/clave_variable.h
index 75cecfd..e568451 100644
--- a/src/clave_variable.h
+++ b/src/clave_variable.h
@@ -8,7 +8,7 @@
 
 /** Representa una clave de longitud variable.
  *
- *  \TODO Usar abreviaciones
+ *  \todo Usar abreviaciones
  */
 class ClaveVariable : public Clave {
 	public :
@@ -20,12 +20,16 @@ class ClaveVariable : public Clave {
 		uchar *ToArray () const;
 		Clave *Clone () const;
 
+		bool Abrev (ClaveVariable *c);
+		bool DesAbrev (ClaveVariable *c);
+
 		virtual bool operator < (const Clave &c) const;
 		virtual bool operator == (const Clave &c) const;
 		virtual operator std::string () const {
 			return data;
 		}
 	private:
+		std::string abreviar(std::string &primera, std::string &actual, int &iguales);
 		std::string data;
 };
 
-- 
2.43.0