Swift: Implement full tree of Assignment classes

Author: geoffw0

swift/ql/lib/codeql/swift/elements/expr/AssignExpr.qll

@@ -1,5 +1,117 @@
 private import codeql.swift.generated.expr.AssignExpr
+private import codeql.swift.elements.expr.BinaryExpr
 
+/**
+ * Any assignment expression. For example:
+ * ```
+ * x = 0
+ * y += 1
+ * z <<= 1
+ * ```
+ */
+class Assignment extends Expr {
+  Assignment() {
+    this instanceof AssignExpr or
+    this instanceof AssignArithmeticOperationEx or
+    this instanceof AssignBitwiseOperationEx
+  }
+
+  /**
+   * Gets the destination of this assignment. For example `x` in:
+   * ```
+   * x = y
+   * ```
+   */
+  Expr getDest() {
+    result = this.(AssignExpr).getDest() or
+    result = this.(AssignOperation).getLeftOperand()
+  }
+
+  /**
+   * Gets the source of this assignment. For example `y` in:
+   * ```
+   * x = y
+   * ```
+   */
+  Expr getSource() {
+    result = this.(AssignExpr).getSource() or
+    result = this.(AssignOperation).getRightOperand()
+  }
+}
+
+/**
+ * A simple assignment expression using the `=` operator:
+ * ```
+ * x = 0
+ * ```
+ */
 class AssignExpr extends Generated::AssignExpr {
   override string toString() { result = " ... = ..." }
 }
+
+/**
+ * Any assignment expression apart from `=`. For example:
+ * ```
+ * x += 1
+ * y &= z
+ * ```
+ */
+class AssignOperation extends Assignment, BinaryExpr {
+  AssignOperation() {
+    this instanceof AssignArithmeticOperationEx or
+    this instanceof AssignBitwiseOperationEx
+  }
+}
+
+/**
+ * An arithmetic assignment expression. For example:
+ * ```
+ * x += 1
+ * y *= z
+ * ```
+ */
+class AssignArithmeticOperation extends AssignOperation instanceof AssignArithmeticOperationEx { }
+
+/**
+ * Private abstract class, extended to define the scope of `AssignArithmeticOperation`.
+ */
+abstract private class AssignArithmeticOperationEx extends BinaryExpr { }
+
+/**
+ * A bitwise assignment expression. For example:
+ * ```
+ * x &= y
+ * z <<= 1
+ * ```
+ */
+class AssignBitwiseOperation extends AssignOperation instanceof AssignBitwiseOperationEx { }
+
+/**
+ * Private abstract class, extended to define the scope of `AssignBitwiseOperation`.
+ */
+abstract private class AssignBitwiseOperationEx extends BinaryExpr { }
+
+/**
+ * An addition assignment expression:
+ * ```
+ * a += b
+ * ```
+ */
+class AssignAddExpr extends AssignArithmeticOperationEx {
+  AssignAddExpr() { this.getOperator().getName() = "+=(_:_:)" }
+
+  override string toString() { result = "... += ..." }
+}
+
+/**
+ * A left-shift assignment expression:
+ * ```
+ * a <<= b
+ * ```
+ */
+class AssignLShiftExpr extends AssignBitwiseOperationEx {
+  AssignLShiftExpr() { this.getOperator().getName() = "<<=(_:_:)" }
+
+  override string toString() { result = "... <<= ..." }
+}
+// TODO ...

swift/ql/test/library-tests/elements/expr/assignment/assignment.expected

@@ -1,2 +1,4 @@
-| assignment.swift:6:2:6:6 |  ... = ... | AssignExpr | x | 1 |
-| assignment.swift:33:2:33:6 |  ... = ... | AssignExpr | y | z |
+| assignment.swift:6:2:6:6 |  ... = ... | AssignExpr, Assignment | x | 1 |
+| assignment.swift:9:2:9:7 | ... += ... | AssignAddExpr, AssignArithmeticOperation, AssignOperation, Assignment | &... | 1 |
+| assignment.swift:19:2:19:8 | ... <<= ... | AssignBitwiseOperation, AssignLShiftExpr, AssignOperation, Assignment | &... | 1 |
+| assignment.swift:33:2:33:6 |  ... = ... | AssignExpr, Assignment | y | z |

swift/ql/test/library-tests/elements/expr/assignment/assignment.ql

@@ -1,10 +1,22 @@
 import swift
 
 string describe(Expr e) {
+  e instanceof Assignment and result = "Assignment"
+  or
+  e instanceof AssignOperation and result = "AssignOperation"
+  or
+  e instanceof AssignArithmeticOperation and result = "AssignArithmeticOperation"
+  or
+  e instanceof AssignBitwiseOperation and result = "AssignBitwiseOperation"
+  or
   e instanceof AssignExpr and result = "AssignExpr"
+  or
+  e instanceof AssignAddExpr and result = "AssignAddExpr"
+  or
+  e instanceof AssignLShiftExpr and result = "AssignLShiftExpr"
 }
 
-from AssignExpr e
+from Assignment e
 where
   e.getLocation().getFile().getBaseName() != ""
 select