PS: More cleanup of AST by fixing up toStrings and adding helper predicates.

powershell/ql/lib/semmle/code/powershell/ArrayExpression.qll

@@ -3,7 +3,7 @@ import powershell
 class ArrayExpr extends @array_expression, Expr {
   override SourceLocation getLocation() { array_expression_location(this, result) }
 
-  StmtBlock getStatementBlock() { array_expression(this, result) }
+  StmtBlock getStmtBlock() { array_expression(this, result) }
 
-  override string toString() { result = "ArrayExpression at: " + this.getLocation().toString() }
+  override string toString() { result = "@(...)" }
 }

powershell/ql/lib/semmle/code/powershell/Attribute.qll

@@ -15,7 +15,11 @@ class Attribute extends @attribute, AttributeBase {
 
   NamedAttributeArgument getANamedArgument() { result = this.getNamedArgument(_) }
 
+  int getNumberOfArguments() { result = count(this.getAPositionalArgument()) }
+
   Expr getPositionalArgument(int i) { attribute_positional_argument(this, i, result) }
 
   Expr getAPositionalArgument() { result = this.getPositionalArgument(_) }
+
+  int getNumberOfPositionalArguments() { result = count(this.getAPositionalArgument()) }
 }

powershell/ql/lib/semmle/code/powershell/CatchClause.qll

@@ -14,4 +14,24 @@ class CatchClause extends @catch_clause, Ast {
   predicate isCatchAll() { catch_clause(this, _, true) } // TODO: Should be equivalent to not exists(this.getACatchType())
 
   TryStmt getTryStmt() { result.getACatchClause() = this }
+
+  predicate isLast() {
+    exists(TryStmt ts, int last |
+      ts = this.getTryStmt() and
+      last = max(int i | exists(ts.getCatchClause(i))) and
+      this = ts.getCatchClause(last)
+    )
+  }
+}
+
+class GeneralCatchClause extends CatchClause {
+  GeneralCatchClause() { this.isCatchAll() }
+
+  override string toString() { result = "catch {...}" }
+}
+
+class SpecificCatchClause extends CatchClause {
+  SpecificCatchClause() { not this.isCatchAll() }
+
+  override string toString() { result = "catch[...] {...}" }
 }

powershell/ql/lib/semmle/code/powershell/Command.qll

@@ -15,9 +15,28 @@ class Cmd extends @command, CmdBase {
 
   CmdElement getElement(int i) { command_command_element(this, i, result) }
 
-  Redirection getRedirection(int i) { command_redirection(this, i, result) }
+  StringConstExpr getCmdName() { result = this.getElement(0) }
 
-  CmdElement getAnElement() { result = this.getElement(_) }
+  Expr getArgument(int i) {
+    result =
+      rank[i + 1](CmdElement e, int j |
+        e = this.getElement(j) and
+        not e instanceof CmdParameter and
+        j > 0 // 0'th element is the command name itself
+      |
+        e order by j
+      )
+  }
+
+  Expr getNamedArgument(string name) {
+    exists(int i, CmdParameter p |
+      this.getElement(i) = p and
+      p.getName() = name and
+      result = p.getArgument()
+    )
+  }
+
+  Redirection getRedirection(int i) { command_redirection(this, i, result) }
 
   Redirection getARedirection() { result = this.getRedirection(_) }
 }

powershell/ql/lib/semmle/code/powershell/CommandParameter.qll

@@ -5,7 +5,19 @@ class CmdParameter extends @command_parameter, CmdElement {
 
   string getName() { command_parameter(this, result) }
 
-  Expr getArgument() { command_parameter_argument(this, result) }
+  Expr getArgument() {
+    // When an argumnt is of the form -Name:$var
+    command_parameter_argument(this, result)
+    or
+    // When an argument is of the form -Name $var
+    exists(int i, Cmd cmd |
+      cmd = this.getCmd() and
+      cmd.getElement(i) = this and
+      result = cmd.getElement(i + 1)
+    )
+  }
+
+  Cmd getCmd() { result.getElement(_) = this }
 
   override string toString() { command_parameter(this, result) }
 }

powershell/ql/lib/semmle/code/powershell/IfStmt.qll

@@ -13,6 +13,10 @@ class IfStmt extends @if_statement, Stmt {
 
   StmtBlock getThen(int i) { if_statement_clause(this, i, _, result) } // TODO: Change @ast to @statement_block in dbscheme
 
+  int getNumberOfConditions() { result = count(this.getACondition()) }
+
+  StmtBlock getAThen() { result = this.getThen(_) }
+
   /** ..., if any. */
   StmtBlock getElse() { if_statement_else(this, result) } // TODO: Change @ast to @stmt_block in dbscheme
 

powershell/ql/lib/semmle/code/powershell/InvokeMemberExpression.qll

@@ -1,9 +1,9 @@
 import powershell
 
-class InvokeMemberExpression extends @invoke_member_expression, MemberExprBase {
+class InvokeMemberExpr extends @invoke_member_expression, MemberExprBase {
   override SourceLocation getLocation() { invoke_member_expression_location(this, result) }
 
-  Expr getExpression() { invoke_member_expression(this, result, _) }
+  Expr getBase() { invoke_member_expression(this, result, _) }
 
   CmdElement getMember() { invoke_member_expression(this, _, result) }
 
@@ -11,5 +11,5 @@ class InvokeMemberExpression extends @invoke_member_expression, MemberExprBase {
 
   Expr getAnArgument() { invoke_member_expression_argument(this, _, result) }
 
-  override string toString() { result = "ArrayExpression at: " + this.getLocation().toString() }
+  override string toString() { result = "call to " + this.getMember() }
 }

powershell/ql/lib/semmle/code/powershell/NamedAttributeArgument.qll

@@ -1,9 +1,9 @@
 import powershell
 
-class NamedAttributeArgument extends @named_attribute_argument {
-  string toString() { result = this.getValue().toString() }
+class NamedAttributeArgument extends @named_attribute_argument, Ast {
+  final override string toString() { result = this.getValue().toString() }
 
-  SourceLocation getLocation() { named_attribute_argument_location(this, result) }
+  final override SourceLocation getLocation() { named_attribute_argument_location(this, result) }
 
   string getName() { named_attribute_argument(this, result, _) }
 

powershell/ql/lib/semmle/code/powershell/StringConstantExpression.qll

@@ -1,10 +1,10 @@
 import powershell
 
-class StringConstExpression extends @string_constant_expression, BaseConstExpr {
+class StringConstExpr extends @string_constant_expression, BaseConstExpr {
   StringLiteral getValue() { string_constant_expression(this, result) }
 
   /** Get the full string literal with all its parts concatenated */
-  override string toString() { result = getValue().toString() }
+  override string toString() { result = this.getValue().toString() }
 
   override SourceLocation getLocation() { string_constant_expression_location(this, result) }
 }

powershell/ql/lib/semmle/code/powershell/StringLiteral.qll

@@ -7,7 +7,11 @@ class StringLiteral extends @string_literal {
 
   /** Get the full string literal with all its parts concatenated */
   string toString() {
-    result = concat(int i | i = [0 .. getNumContinuations()] | getContinuation(i), "\n")
+    result = this.getValue()
+  }
+
+  string getValue() {
+    result = concat(int i | i = [0 .. this.getNumContinuations()] | this.getContinuation(i), "\n")
   }
 
   SourceLocation getLocation() { string_literal_location(this, result) }

powershell/ql/lib/semmle/code/powershell/TryStmt.qll

@@ -14,4 +14,5 @@ class TryStmt extends @try_statement, Stmt {
 
   StmtBlock getBody() { try_statement(this, result) } // TODO: Change @ast to @stmt_block in dbscheme
 
+  predicate hasFinally() { exists(this.getFinally()) }
 }