import python

private import semmle.python.SelfAttribute

/** The metrics for a function */

class FunctionMetrics extends Function {

/**

* Gets the total number of lines (including blank lines)

* from the definition to the end of the function

*/

int getNumberOfLines() { py_alllines(this, result) }

/** Gets the number of lines of code in the function */

int getNumberOfLinesOfCode() { py_codelines(this, result) }

/** Gets the number of lines of comments in the function */

int getNumberOfLinesOfComments() { py_commentlines(this, result) }

/** Gets the number of lines of docstring in the function */

int getNumberOfLinesOfDocStrings() { py_docstringlines(this, result) }

int getNumberOfParametersWithoutDefault() {

result =

this.getPositionalParameterCount() -

count(this.getDefinition().(FunctionExpr).getArgs().getADefault())

}

int getStatementNestingDepth() { result = max(Stmt s | s.getScope() = this | getNestingDepth(s)) }

int getNumberOfCalls() { result = count(Call c | c.getScope() = this) }

}

/** The metrics for a class */

class ClassMetrics extends Class {

/**

* Gets the total number of lines (including blank lines)

* from the definition to the end of the class

*/

int getNumberOfLines() { py_alllines(this, result) }

/** Gets the number of lines of code in the class */

int getNumberOfLinesOfCode() { py_codelines(this, result) }

/** Gets the number of lines of comments in the class */

int getNumberOfLinesOfComments() { py_commentlines(this, result) }

/** Gets the number of lines of docstrings in the class */

int getNumberOfLinesOfDocStrings() { py_docstringlines(this, result) }

/* -------- CHIDAMBER AND KEMERER LACK OF COHESION IN METHODS ------------ */

/*

* The aim of this metric is to try and determine whether a class

* represents one abstraction (good) or multiple abstractions (bad).

* If a class represents multiple abstractions, it should be split

* up into multiple classes.

*

* In the Chidamber and Kemerer method, this is measured as follows:

* n1 = number of pairs of distinct methods in a class that do *not*

* have at least one commonly accessed field

* n2 = number of pairs of distinct methods in a class that do

* have at least one commonly accessed field

* lcom = ((n1 - n2)/2 max 0)

*

* We divide by 2 because each pair (m1,m2) is counted twice in n1 and n2.

*/

/** should function f be excluded from the cohesion computation? */

predicate ignoreLackOfCohesion(Function f) { f.isInitMethod() or f.isSpecialMethod() }

private predicate methodPair(Function m1, Function m2) {

m1.getScope() = this and

m2.getScope() = this and

not this.ignoreLackOfCohesion(m1) and

not this.ignoreLackOfCohesion(m2) and

m1 != m2

}

private predicate one_accesses_other(Function m1, Function m2) {

this.methodPair(m1, m2) and

(

exists(SelfAttributeRead sa |

sa.getName() = m1.getName() and

sa.getScope() = m2

)

or

exists(SelfAttributeRead sa |

sa.getName() = m2.getName() and

sa.getScope() = m1

)

)

}

/** do m1 and m2 access a common field or one calls the other? */

private predicate shareField(Function m1, Function m2) {

this.methodPair(m1, m2) and

exists(string name |

exists(SelfAttributeRead sa |

sa.getName() = name and

sa.getScope() = m1

) and

exists(SelfAttributeRead sa |

sa.getName() = name and

sa.getScope() = m2

)

)

}

private int similarMethodPairs() {

result =

count(Function m1, Function m2 |

this.methodPair(m1, m2) and

(this.shareField(m1, m2) or this.one_accesses_other(m1, m2))

) / 2

}

private int methodPairs() {

result = count(Function m1, Function m2 | this.methodPair(m1, m2)) / 2

}

/** return Chidamber and Kemerer Lack of Cohesion */

int getLackOfCohesionCK() {

exists(int n |

n = this.methodPairs() - 2 * this.similarMethodPairs() and

result = n.maximum(0)

)

}

private predicate similarMethodPairDag(Function m1, Function m2, int line) {

(this.shareField(m1, m2) or this.one_accesses_other(m1, m2)) and

line = m1.getLocation().getStartLine() and

line < m2.getLocation().getStartLine()

}

private predicate subgraph(Function m, int line) {

this.similarMethodPairDag(m, _, line) and not this.similarMethodPairDag(_, m, _)

or

exists(Function other | this.subgraph(other, line) |

this.similarMethodPairDag(other, m, _) or

this.similarMethodPairDag(m, other, _)

)

}

predicate unionSubgraph(Function m, int line) { line = min(int l | this.subgraph(m, l)) }

/** return Hitz and Montazeri Lack of Cohesion */

int getLackOfCohesionHM() { result = count(int line | this.unionSubgraph(_, line)) }

}

class ModuleMetrics extends Module {

/** Gets the total number of lines (including blank lines) in the module */

int getNumberOfLines() { py_alllines(this, result) }

/** Gets the number of lines of code in the module */

int getNumberOfLinesOfCode() { py_codelines(this, result) }

/** Gets the number of lines of comments in the module */

int getNumberOfLinesOfComments() { py_commentlines(this, result) }

/** Gets the number of lines of docstrings in the module */

int getNumberOfLinesOfDocStrings() { py_docstringlines(this, result) }

}

predicate non_coupling_method(Function f) {

f.isSpecialMethod() or

f.isInitMethod() or

f.getName() = "close" or

f.getName() = "write" or

f.getName() = "read" or

f.getName() = "get" or

f.getName() = "set"

}

private int getNestingDepth(Stmt s) {

not exists(Stmt outer | outer.getASubStatement() = s) and result = 1

or

exists(Stmt outer | outer.getASubStatement() = s |

if s.(If).isElif() or s instanceof ExceptStmt

then

/* If statement is an `elif` or `except` then it is not indented relative to its parent */

result = getNestingDepth(outer)

else result = getNestingDepth(outer) + 1

)

}