Move 'snippet' queries to 'snippets' folders

java/ql/examples/snippets/arrayaccess.ql

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+/**
+ * @name Array access
+ * @description Finds array access expressions with an index expression
+ *              consisting of a unary assignment
+ * @tags array
+ *       access
+ *       index
+ *       unary
+ *       assignment
+ */
+
+import java
+
+from ArrayAccess a
+where a.getIndexExpr() instanceof UnaryAssignExpr
+select a

java/ql/examples/snippets/castexpr.ql

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+/**
+ * @name Cast expressions
+ * @description Finds casts from a floating point type to an integer type
+ * @tags cast
+ *       integer
+ *       float
+ *       type
+ */
+
+import java
+
+from CastExpr c
+where c.getExpr().getType() instanceof FloatingPointType
+  and c.getType() instanceof IntegralType
+select c

java/ql/examples/snippets/catch_exception.ql

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+/**
+ * @name Catch exception
+ * @description Finds places where we catch exceptions of type com.example.AnException
+ * @tags catch
+ *       try
+ *       exception
+ */
+ 
+import java
+
+from CatchClause catch
+where catch.getACaughtType().hasQualifiedName("com.example", "AnException")
+select catch

java/ql/examples/snippets/constructor_call.ql

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+/**
+ * @name Call to constructor
+ * @description Finds places where we call `new com.example.Class(...)`
+ * @tags call
+ *       constructor
+ *       new
+ */
+ 
+import java
+
+from ClassInstanceExpr new
+where new.getConstructedType().hasQualifiedName("com.example", "Class")
+select new

java/ql/examples/snippets/emptyblock.ql

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+/**
+ * @name Empty blocks
+ * @description Finds empty block statements
+ * @tags empty
+ *       block
+ *       statement
+ */
+
+import java
+
+from Block blk
+where blk.getNumStmt() = 0
+select blk

java/ql/examples/snippets/emptythen.ql

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+/**
+ * @name If statements with empty then branch
+ * @description Finds 'if' statements where the 'then' branch is
+ *              an empty block statement
+ * @tags if
+ *       then
+ *       empty
+ *       conditional
+ *       branch
+ */
+
+import java
+
+from IfStmt i
+where i.getThen().(Block).getNumStmt() = 0
+select i

java/ql/examples/snippets/eq_true.ql

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+/**
+ * @name Equality test on boolean
+ * @description Finds tests like `==true`, `==false`, `!=true`, `!=false`
+ * @tags equals
+ *       test
+ *       boolean
+ */
+ 
+import java
+
+from EqualityTest eq
+where eq.getAnOperand() instanceof BooleanLiteral
+select eq

java/ql/examples/snippets/extend_class.ql

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+/**
+ * @name Class extends/implements
+ * @description Finds classes/interfaces that extend/implement com.example.Class
+ * @tags class
+ *       extends
+ *       implements
+ *       overrides
+ *       subtype
+ *       supertype
+ */
+ 
+import java
+
+from RefType type
+where type.getASupertype+().hasQualifiedName("com.example", "Class")
+select type

java/ql/examples/snippets/field_read.ql

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+/**
+ * @name Read of field
+ * @description Finds reads of aField (defined on com.example.Class)
+ * @tags field
+ *       read
+ */
+ 
+import java
+
+from Field f, FieldRead read
+where f.hasName("aField")
+  and f.getDeclaringType().hasQualifiedName("com.example", "Class")
+  and f = read.getField()
+select read

java/ql/examples/snippets/integer_literal.ql

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+/**
+ * @name Integer literal
+ * @description Finds places where we use the integer literal `0`
+ * @tags integer
+ *       literal
+ */
+ 
+import java
+
+from IntegerLiteral literal
+where literal.getLiteral().toInt() = 0
+select literal

java/ql/examples/snippets/method_call.ql

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+/**
+ * @name Call to method
+ * @description Finds calls to com.example.Class.methodName
+ * @tags call
+ *       method
+ */
+ 
+import java
+
+from MethodAccess call, Method method
+where call.getMethod() = method
+  and method.hasName("methodName")
+  and method.getDeclaringType().hasQualifiedName("com.example", "Class")
+select call

java/ql/examples/snippets/mutualrecursion.ql

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+/**
+ * @name Mutual recursion
+ * @description Finds pairs of methods that call each other
+ * @tags method
+ *       recursion
+ */
+
+import java
+
+from Method m, Method n
+where exists(MethodAccess ma | ma.getCaller() = m and ma.getCallee() = n)
+  and exists(MethodAccess ma | ma.getCaller() = n and ma.getCallee() = m)
+  and m != n
+select m, n

java/ql/examples/snippets/nativemethod.ql

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+/**
+ * @name Native methods
+ * @description Finds methods that are native
+ * @tags method
+ *       native
+ *       modifier
+ */
+
+import java
+
+from Method m
+where m.isNative()
+select m

java/ql/examples/snippets/null_argument.ql

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+/**
+ * @name Add null to collection
+ * @description Finds places where we add null to a collection
+ * @tags null
+ *       parameter
+ *       argument
+ *       collection
+ *       add
+ */
+ 
+import java
+
+from MethodAccess call, Method add
+where call.getMethod().overrides*(add)
+  and add.hasName("add")
+  and add.getDeclaringType().getSourceDeclaration().hasQualifiedName("java.util", "Collection")
+  and call.getAnArgument() instanceof NullLiteral
+select call

java/ql/examples/snippets/override_method.ql

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+/**
+ * @name Override of method
+ * @description Finds methods that override com.example.Class.baseMethod
+ * @tags method
+ *       override
+ */
+ 
+import java
+
+from Method override, Method base
+where base.hasName("baseMethod")
+  and base.getDeclaringType().hasQualifiedName("com.example", "Class")
+  and override.overrides+(base)
+select override

java/ql/examples/snippets/qualifiedthis.ql

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+/**
+ * @name Qualified 'this' access
+ * @description Finds 'this' accesses that are qualified by a type name
+ * @tags this
+ *       access
+ *       qualifier
+ */
+
+import java
+
+from ThisAccess t
+where exists(t.getQualifier())
+select t

java/ql/examples/snippets/returnstatement.ql

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+/**
+ * @name Return statements
+ * @description Finds return statements that return 'null'
+ * @tags return
+ *       statement
+ *       null
+ */
+
+import java
+
+from ReturnStmt r
+where r.getResult() instanceof NullLiteral
+select r

java/ql/examples/snippets/singletonblock.ql

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+/**
+ * @name Singleton blocks
+ * @description Finds block statements containing a single statement
+ * @tags block
+ *       statement
+ */
+
+import java
+
+from Block b
+where b.getNumStmt() = 1
+select b

java/ql/examples/snippets/switchcase.ql

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+/**
+ * @name Switch statement case missing
+ * @description Finds switch statements with a missing enum constant case and no default case
+ * @tags switch
+ *       case
+ *       enum
+ */
+
+import java
+
+from SwitchStmt switch, EnumType enum, EnumConstant missing
+where switch.getExpr().getType() = enum
+  and missing.getDeclaringType() = enum
+  and not switch.getAConstCase().getValue() = missing.getAnAccess()
+  and not exists(switch.getDefaultCase())
+select switch

java/ql/examples/snippets/synchronizedmethod.ql

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+/**
+ * @name Synchronized methods
+ * @description Finds methods that are synchronized
+ * @tags method
+ *       synchronized
+ *       modifier
+ */
+
+import java
+
+from Method m
+where m.isSynchronized()
+select m

java/ql/examples/snippets/ternaryconditional.ql

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+/**
+ * @name Conditional expressions
+ * @description Finds conditional expressions of the form '... ? ... : ...'
+ *              where the types of the resulting expressions differ
+ * @tags conditional
+ *       type
+ */
+
+import java
+
+from ConditionalExpr e
+where e.getTrueExpr().getType() != e.getFalseExpr().getType()
+  and not e.getTrueExpr().getType() instanceof NullType
+  and not e.getFalseExpr().getType() instanceof NullType
+select e

java/ql/examples/snippets/throw_exception.ql

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+/**
+ * @name Throw exception of type
+ * @description Finds places where we throw com.example.AnException or one of its subtypes
+ * @tags throw
+ *       exception
+ */
+ 
+import java
+
+from ThrowStmt throw
+where throw.getThrownExceptionType().getASupertype*().hasQualifiedName("com.example", "AnException")
+select throw, "Don't throw com.example.AnException"

java/ql/examples/snippets/todocomment.ql

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+/**
+ * @name TODO comments
+ * @description Finds comments containing the word "TODO"
+ * @tags comment
+ *       TODO
+ */
+
+import java
+
+from JavadocText c
+where c.getText().regexpMatch("(?si).*\\bTODO\\b.*")
+select c

java/ql/examples/snippets/toomanyparams.ql

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+/**
+ * @name Methods with many parameters
+ * @description Finds methods with more than ten parameters
+ * @tags method
+ *       parameter
+ *       argument
+ */
+
+import java
+
+from Method m
+where m.getNumberOfParameters() > 10
+select m

java/ql/examples/snippets/tryfinally.ql

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+/**
+ * @name Try-finally statements
+ * @description Finds try-finally statements without a catch clause
+ * @tags try
+ *       finally
+ *       catch
+ *       exceptions
+ */
+
+import java
+
+from TryStmt t
+where exists(t.getFinally())
+  and not exists(t.getACatchClause())
+select t

java/ql/examples/snippets/unusedlocalvar.ql

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+/**
+ * @name Unused local variable
+ * @description Finds local variables that are not accessed
+ * @tags variable
+ *       local
+ *       access
+ */
+
+import java
+
+from LocalVariableDecl v
+where not exists(v.getAnAccess())
+select v

java/ql/examples/snippets/unusedmethod.ql

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+/**
+ * @name Unused private method
+ * @description Finds private methods that are not accessed
+ * @tags method
+ *       access
+ *       private
+ */
+
+import java
+
+from Method m
+where m.isPrivate()
+  and not exists(m.getAReference())
+  and not m instanceof InitializerMethod
+select m

java/ql/examples/snippets/unusedparam.ql

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+/**
+ * @name Unused parameter
+ * @description Finds parameters that are not accessed
+ * @tags parameter
+ *       access
+ */
+
+import java
+
+from Parameter p
+where not exists(p.getAnAccess())
+select p

java/ql/examples/snippets/voidreturntype.ql

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+/**
+ * @name Methods without return type
+ * @description Finds methods whose return type is 'void'
+ * @tags method
+ *       void
+ *       modifier
+ *       return
+ *       type
+ */
+
+import java
+
+from Method m
+where m.getReturnType() instanceof VoidType
+select m

java/ql/examples/snippets/volatilefield.ql

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+/**
+ * @name Fields declared volatile
+ * @description Finds fields with a 'volatile' modifier
+ * @tags field
+ *       volatile
+ *       synchronization
+ */
+
+import java
+
+from Field f
+where f.isVolatile()
+select f