Refactor to use isValid() check to simplify checking pointers before every C call

Author: justinfx

pigosat.go

@@ -147,7 +147,7 @@ func (p *Pigosat) isValid() bool {
 // sure, it's always safe to call Delete again). Most users will not need this
 // method.
 func (p *Pigosat) Delete() {
-	if p == nil || p.p == nil {
+	if !p.isValid() {
 		return
 	}
 	p.lock.Lock()
@@ -164,7 +164,7 @@ func (p *Pigosat) Delete() {
 // Variables returns the number of variables in the formula: The m in the DIMACS
 // header "p cnf <m> n".
 func (p *Pigosat) Variables() int {
-	if p == nil || p.p == nil {
+	if !p.isValid() {
 		return 0
 	}
 	p.lock.RLock()
@@ -176,7 +176,7 @@ func (p *Pigosat) Variables() int {
 // AddedOriginalClauses returns the number of clauses in the formula: The n in
 // the DIMACS header "p cnf m <n>".
 func (p *Pigosat) AddedOriginalClauses() int {
-	if p == nil || p.p == nil {
+	if !p.isValid() {
 		return 0
 	}
 	p.lock.RLock()
@@ -187,7 +187,7 @@ func (p *Pigosat) AddedOriginalClauses() int {
 
 // Seconds returns the time spent in the PicoSAT library.
 func (p *Pigosat) Seconds() time.Duration {
-	if p == nil || p.p == nil {
+	if !p.isValid() {
 		return 0
 	}
 	p.lock.RLock()
@@ -205,7 +205,7 @@ func (p *Pigosat) Seconds() time.Duration {
 // the clause, and causes AddClauses to skip reading the rest of the slice. Nil
 // slices are ignored and skipped.
 func (p *Pigosat) AddClauses(clauses [][]int32) {
-	if p == nil || p.p == nil {
+	if !p.isValid() {
 		return
 	}
 	p.lock.Lock()
@@ -247,7 +247,7 @@ func (p *Pigosat) blocksol(sol []bool) {
 //        // Do stuff with status, solution
 //    }
 func (p *Pigosat) Solve() (status int, solution []bool) {
-	if p == nil || p.p == nil {
+	if !p.isValid() {
 		return NotReady, nil
 	}
 	p.lock.Lock()
@@ -280,7 +280,7 @@ func (p *Pigosat) Solve() (status int, solution []bool) {
 // length. There is no need to call BlockSolution after calling Pigosat.Solve,
 // which calls it automatically for every Satisfiable solution.
 func (p *Pigosat) BlockSolution(solution []bool) error {
-	if p == nil || p.p == nil {
+	if !p.isValid() {
 		return nil
 	}
 	p.lock.Lock()