Remove redundant nil check (#1367)

From the Go docs [1]: "1. For a nil slice, the number of iterations is 0." "3. If the map is nil, the number of iterations is 0." Therefore, an additional nil check for before the loop is unnecessary. [1]: https://go.dev/ref/spec#For_range Signed-off-by: Eng Zer Jun <[email protected]>
johnkerl · Aug 23, 2023 · 12f3b14 · 12f3b14
1 parent 9ad9e21
commit 12f3b14
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Showing 5 changed files with 93 additions and 109 deletions.
diff --git a/internal/pkg/cli/flag_types.go b/internal/pkg/cli/flag_types.go
@@ -398,11 +398,9 @@ func (flag *Flag) Owns(input string) bool {
 	if flag.name == input {
 		return true
 	}
-	if flag.altNames != nil {
-		for _, name := range flag.altNames {
-			if name == input {
-				return true
-			}
+	for _, name := range flag.altNames {
+		if name == input {
+			return true
 		}
 	}
 	return false
@@ -414,11 +412,9 @@ func (flag *Flag) Matches(input string) bool {
 	if strings.Contains(flag.name, input) {
 		return true
 	}
-	if flag.altNames != nil {
-		for _, name := range flag.altNames {
-			if strings.Contains(name, input) {
-				return true
-			}
+	for _, name := range flag.altNames {
+		if strings.Contains(name, input) {
+			return true
 		}
 	}
 	return false

diff --git a/internal/pkg/dsl/ast_print.go b/internal/pkg/dsl/ast_print.go
@@ -75,10 +75,8 @@ func (node *ASTNode) printAux(depth int) {
 	fmt.Println()
 
 	// Children, indented one level further
-	if node.Children != nil {
-		for _, child := range node.Children {
-			child.printAux(depth + 1)
-		}
+	for _, child := range node.Children {
+		child.printAux(depth + 1)
 	}
 }
 

diff --git a/internal/pkg/dsl/cst/for.go b/internal/pkg/dsl/cst/for.go
@@ -887,12 +887,10 @@ func (node *TripleForLoopNode) Execute(state *runtime.State) (*BlockExitPayload,
 	}
 
 	for {
-		if node.precontinuationAssignments != nil {
-			for _, precontinuationAssignment := range node.precontinuationAssignments {
-				_, err := precontinuationAssignment.Execute(state)
-				if err != nil {
-					return nil, err
-				}
+		for _, precontinuationAssignment := range node.precontinuationAssignments {
+			_, err := precontinuationAssignment.Execute(state)
+			if err != nil {
+				return nil, err
 			}
 		}
 		if node.continuationExpressionNode != nil { // empty is true

diff --git a/internal/pkg/dsl/cst/validate.go b/internal/pkg/dsl/cst/validate.go
@@ -35,23 +35,21 @@ func ValidateAST(
 		}
 	}
 
-	if ast.RootNode.Children != nil {
-		for _, astChild := range ast.RootNode.Children {
-			err := validateASTAux(
-				astChild,
-				dslInstanceType,
-				atTopLevel,
-				inLoop,
-				inBeginOrEnd,
-				inUDF,
-				inUDS,
-				isMainBlockLastStatement,
-				isAssignmentLHS,
-				isUnset,
-			)
-			if err != nil {
-				return err
-			}
+	for _, astChild := range ast.RootNode.Children {
+		err := validateASTAux(
+			astChild,
+			dslInstanceType,
+			atTopLevel,
+			inLoop,
+			inBeginOrEnd,
+			inUDF,
+			inUDS,
+			isMainBlockLastStatement,
+			isAssignmentLHS,
+			isUnset,
+		)
+		if err != nil {
+			return err
 		}
 	}
 
@@ -219,25 +217,23 @@ func validateASTAux(
 	//  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 	// Treewalk
 
-	if astNode.Children != nil {
-		for i, astChild := range astNode.Children {
-			nextLevelIsAssignmentLHS = astNode.Type == dsl.NodeTypeAssignment && i == 0
-			nextLevelIsUnset = astNode.Type == dsl.NodeTypeUnset
-			err := validateASTAux(
-				astChild,
-				dslInstanceType,
-				nextLevelAtTopLevel,
-				nextLevelInLoop,
-				nextLevelInBeginOrEnd,
-				nextLevelInUDF,
-				nextLevelInUDS,
-				isMainBlockLastStatement,
-				nextLevelIsAssignmentLHS,
-				nextLevelIsUnset,
-			)
-			if err != nil {
-				return err
-			}
+	for i, astChild := range astNode.Children {
+		nextLevelIsAssignmentLHS = astNode.Type == dsl.NodeTypeAssignment && i == 0
+		nextLevelIsUnset = astNode.Type == dsl.NodeTypeUnset
+		err := validateASTAux(
+			astChild,
+			dslInstanceType,
+			nextLevelAtTopLevel,
+			nextLevelInLoop,
+			nextLevelInBeginOrEnd,
+			nextLevelInUDF,
+			nextLevelInUDS,
+			isMainBlockLastStatement,
+			nextLevelIsAssignmentLHS,
+			nextLevelIsUnset,
+		)
+		if err != nil {
+			return err
 		}
 	}
 

diff --git a/internal/pkg/dsl/cst/warn.go b/internal/pkg/dsl/cst/warn.go
@@ -24,16 +24,14 @@ func WarnOnAST(
 	inAssignment := false
 	ok := true
 
-	if ast.RootNode.Children != nil {
-		for _, astChild := range ast.RootNode.Children {
-			ok1 := warnOnASTAux(
-				astChild,
-				variableNamesWrittenTo,
-				inAssignment,
-			)
-			// Don't end early on first warning; tree-walk to list them all.
-			ok = ok1 && ok
-		}
+	for _, astChild := range ast.RootNode.Children {
+		ok1 := warnOnASTAux(
+			astChild,
+			variableNamesWrittenTo,
+			inAssignment,
+		)
+		// Don't end early on first warning; tree-walk to list them all.
+		ok = ok1 && ok
 	}
 
 	return ok
@@ -134,52 +132,50 @@ func warnOnASTAux(
 
 	// Treewalk to check the rest of the AST below this node.
 
-	if astNode.Children != nil {
-		for i, astChild := range astNode.Children {
-			childInAssignment := inAssignment
-
-			if astNode.Type == dsl.NodeTypeAssignment && i == 0 {
-				// LHS of assignment statements
-				childInAssignment = true
-			} else if astNode.Type == dsl.NodeTypeForLoopOneVariable && i == 0 {
-				// The 'k' in 'for (k in $*)'
-				childInAssignment = true
-			} else if astNode.Type == dsl.NodeTypeForLoopTwoVariable && (i == 0 || i == 1) {
-				// The 'k' and 'v' in 'for (k,v in $*)'
-				childInAssignment = true
-			} else if astNode.Type == dsl.NodeTypeForLoopMultivariable && (i == 0 || i == 1) {
-				// The 'k1', 'k2', and 'v' in 'for ((k1,k2),v in $*)'
-				childInAssignment = true
-			} else if astNode.Type == dsl.NodeTypeParameterList {
+	for i, astChild := range astNode.Children {
+		childInAssignment := inAssignment
+
+		if astNode.Type == dsl.NodeTypeAssignment && i == 0 {
+			// LHS of assignment statements
+			childInAssignment = true
+		} else if astNode.Type == dsl.NodeTypeForLoopOneVariable && i == 0 {
+			// The 'k' in 'for (k in $*)'
+			childInAssignment = true
+		} else if astNode.Type == dsl.NodeTypeForLoopTwoVariable && (i == 0 || i == 1) {
+			// The 'k' and 'v' in 'for (k,v in $*)'
+			childInAssignment = true
+		} else if astNode.Type == dsl.NodeTypeForLoopMultivariable && (i == 0 || i == 1) {
+			// The 'k1', 'k2', and 'v' in 'for ((k1,k2),v in $*)'
+			childInAssignment = true
+		} else if astNode.Type == dsl.NodeTypeParameterList {
+			childInAssignment = true
+		} else if inAssignment && astNode.Type == dsl.NodeTypeArrayOrMapIndexAccess {
+			// In 'z[i] = 1', the 'i' is a read and the 'z' is a write.
+			//
+			// mlr --from r put -v -W 'z[i] = 1'
+			// DSL EXPRESSION:
+			// z[i]=1
+			//
+			// AST:
+			// * statement block
+			//     * assignment "="
+			//         * array or map index access "[]"
+			//             * local variable "z"
+			//             * local variable "i"
+			//         * int literal "1"
+			if i == 0 {
 				childInAssignment = true
-			} else if inAssignment && astNode.Type == dsl.NodeTypeArrayOrMapIndexAccess {
-				// In 'z[i] = 1', the 'i' is a read and the 'z' is a write.
-				//
-				// mlr --from r put -v -W 'z[i] = 1'
-				// DSL EXPRESSION:
-				// z[i]=1
-				//
-				// AST:
-				// * statement block
-				//     * assignment "="
-				//         * array or map index access "[]"
-				//             * local variable "z"
-				//             * local variable "i"
-				//         * int literal "1"
-				if i == 0 {
-					childInAssignment = true
-				} else {
-					childInAssignment = false
-				}
+			} else {
+				childInAssignment = false
 			}
-			ok1 := warnOnASTAux(
-				astChild,
-				variableNamesWrittenTo,
-				childInAssignment,
-			)
-			// Don't end early on first error; tree-walk to list them all.
-			ok = ok1 && ok
 		}
+		ok1 := warnOnASTAux(
+			astChild,
+			variableNamesWrittenTo,
+			childInAssignment,
+		)
+		// Don't end early on first error; tree-walk to list them all.
+		ok = ok1 && ok
 	}
 
 	return ok