From 5d476f9a0cea30dc5e29ec9e80a58ee912e9758a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rajmund=20Hru=C5=A1ka?= <rajmund.hruska@gmail.com>
Date: Mon, 4 May 2020 17:59:02 +0200
Subject: [PATCH] algo: covers: Add documenation to approximate enhanced covers
---
.../cover/ApproximateEnhancedCoversCommon.h | 43 +++++++++++++++++++
.../ApproximateEnhancedCoversComputation.h | 25 ++++++++++-
2 files changed, 66 insertions(+), 2 deletions(-)
diff --git a/alib2algo/src/stringology/cover/ApproximateEnhancedCoversCommon.h b/alib2algo/src/stringology/cover/ApproximateEnhancedCoversCommon.h
index f0e3d6e5a3..0104ea3189 100644
--- a/alib2algo/src/stringology/cover/ApproximateEnhancedCoversCommon.h
+++ b/alib2algo/src/stringology/cover/ApproximateEnhancedCoversCommon.h
@@ -10,12 +10,19 @@ namespace stringology::cover {
class ApproximateEnhancedCoversCommon {
protected:
+ /**
+ * A simple structure used to represent the element of d-subset corresponding
+ * to a state q of a nondeterministic finite automaton.
+ */
struct Element {
unsigned depth, level;
Element ( ) = default;
Element ( unsigned d, unsigned l ) : depth ( d ), level ( l ) { }
};
+ /**
+ * State of the deterministic trie-like k-approximate suffix automaton.
+ */
template < class SymbolType >
struct State {
unsigned depth = 0;
@@ -23,12 +30,48 @@ protected:
ext::vector < Element > elements;
};
+ /**
+ * Computes the number of covered positions by the given state.
+ *
+ * @param q state of the deterministic k-approximate suffix automaton
+ * @return the number of covered positions
+ */
template < class SymbolType >
static unsigned distEnhCov ( State < SymbolType > const * q );
+
+ /**
+ * Computes the number of covered positions by the given state and updates the
+ * set of found (relaxed) k-approximate enhanced covers if necessary.
+ *
+ * @param state
+ * @param enhCovers set of all (relaxed) k-approximate enhanced covers
+ * @param h the maximum number of covered position
+ */
template < class SymbolType >
static void updateEnhCov ( State < SymbolType > const * state, ext::set < string::LinearString < SymbolType > > & enhCovers, unsigned & h );
+
+ /**
+ * Constructs the first state of deterministic k-approximate suffix automaton
+ * obtained by reading symbol "symbol".
+ *
+ * @param x the original string
+ * @param k the maximum number of allowed errors
+ * @param symbol the first read symbol
+ * @return the first state of deterministic k-approximate suffix automaton
+ */
template < class SymbolType >
static State < SymbolType > * constrFirstState ( const string::LinearString < SymbolType > & x, unsigned k, const SymbolType & symbol );
+
+ /**
+ * Constructs the next state of deterministic k-approximate suffix automaton
+ * approachable by the previous state by reading the symbol "symbol".
+ *
+ * @param x the original string
+ * @param previousState
+ * @param k the maximum number of allowed errors
+ * @param symbol read symbol
+ * @return the next state of deterministic k-approximate suffix automaton
+ */
template < class SymbolType >
static State < SymbolType > * constrNextState ( const string::LinearString < SymbolType > & x, State < SymbolType > const * previousState, unsigned k, const SymbolType & symbol );
};
diff --git a/alib2algo/src/stringology/cover/ApproximateEnhancedCoversComputation.h b/alib2algo/src/stringology/cover/ApproximateEnhancedCoversComputation.h
index 3809f48b82..58657e3604 100644
--- a/alib2algo/src/stringology/cover/ApproximateEnhancedCoversComputation.h
+++ b/alib2algo/src/stringology/cover/ApproximateEnhancedCoversComputation.h
@@ -6,13 +6,32 @@
#include <stringology/cover/ApproximateEnhancedCoversCommon.h>
namespace stringology::cover {
-
+/**
+ * Computation of all k-approximate enhanced covers under Hamming distance.
+ */
class ApproximateEnhancedCoversComputation : ApproximateEnhancedCoversCommon {
public:
+ /**
+ * Computes all k-approximate enhanced covers under Hamming distance.
+ *
+ * @param x the original string for which k-approximate enhanced covers are
+ * computed
+ * @param k the maximum number of allowed errors
+ * @return set of all k-approximate enhanced covers under Hamming distance
+ */
template < class SymbolType >
static ext::set < string::LinearString < SymbolType > > compute ( const string::LinearString < SymbolType > & x, unsigned k );
private:
+ /**
+ * Checks if a string represented by the state of the backbone of
+ * k-approximate deterministic suffix automaton is a border.
+ *
+ * @param state
+ * @param x the original string
+ * @param k maximum number of allowed errors
+ * @return true if state represents border, false otherwise
+ */
template < class SymbolType >
static bool isBorder ( State < SymbolType > const * state, const string::LinearString < SymbolType > & x, unsigned k );
};
@@ -24,13 +43,15 @@ ext::set < string::LinearString < SymbolType > > ApproximateEnhancedCoversComput
// the maximum number of covered positions
unsigned h = 0;
+ // there are no borders for an empty string and a string with only one
+ // character
if ( x.getContent ( ).size ( ) < 2 )
return result;
State < SymbolType > * previousState = constrFirstState ( x, k, x.getContent ( )[0] );
State < SymbolType > * nextState = nullptr;
- // check if the the first character is a border (makes sense only for k = 0)
+ // check if the first character is a border (makes sense only for k = 0)
if ( isBorder ( previousState, x, k ) )
updateEnhCov ( previousState, result, h );
--
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