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| Language.Sdf.Metrics.Halstead | | Portability | portable
| | Stability | experimental
| | Maintainer | Tiago Alves and Joost Visser
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| Description |
| Halstead metrics for Sdf grammars, taken from:
http://mdp.ivv.nasa.gov/halstead_metrics.html
http://www.sei.cmu.edu/str/descriptions/halstead_body.html
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| Synopsis |
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| Representation |
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| data HalsteadMetrics |
| Data type to hold all metric results | | Constructors | | HalsteadMetrics | | | u1 :: Int | Number of Distinct Operators | | u2 :: Int | Number of Distinct Operands | | n1 :: Int | Total Number of Operators | | n2 :: Int | Total Number of Operands | | pn :: Int | Program Vocabulary (n = n1 + n2) | | pN :: Int | Program Length (N = N1 + N2) | | pV :: Float | Program Volume (V = N * LOG2 n) | | pD :: Float | Program Difficulty (D = (n1/2) * (N2/n2)) | | pE :: Float | Program Effort (E = D * V) | | pL :: Float | Program Level (L = (2/n1) * (n2/N2)) | | pT :: Float | Programming Time (T = E/18) |
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| halsteadMetrics :: HalsteadMetrics -> GroupMetric |
| Creates a uniform representation of the metrics converting the internal
HalsteadMetrics record to a GroupMetric type which holds not only all
the calculated metric values but also all information about the metrics:
description and name. |
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| Function to calculate all metrics |
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| calcHalsteadMetrics :: SDF -> HalsteadMetrics |
| Calculates all Halstead metrics |
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| Functions to separate Operators and Operands |
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| calcOperatorsAndOperands :: [Production] -> ([Int], [String]) |
| Calculates all operators and operands from a list of productions.
Each operator will be represented by its key (an unique number) and
for each operand its value (string) will be used. |
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| sepOperatorsAndOperands :: Production -> [Either Int String] |
| Separate Operators and Operands from an SDF Production. |
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| sepOaOfromSymb :: Symbol -> [Either Int String] |
| Separate Operators and Operands of an SDF Symbol by recursively transverse
the Symbol data-type. For each operator returns its key (number) and for
each operand returns its value. |
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| sepOaOfromLstSymbs :: [Symbol] -> [Either Int String] |
| Separates the operators and operands from a list of symbols. This function
counts the invisible concatenation operator and invokes the
sepOaOfromSymb function to traverse the Symbol data type. |
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| Individual metric calculation functions |
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| calcVolume :: Int -> Int -> Float |
Calculates the Halstead Program Volume
Halstead Program Volume is calculated by the following formula:
N * log2 nÊ where
- N = Program Length
- n = Program Vocabulary
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| calcDifficulty :: Int -> Int -> Int -> Float |
Calculates the Halstead Program Difficulty
Halstead Program Difficulty is calculated by the following formula:
(u1 / 2) * (n2 / u2) where
- u1 = Number of Distinct Operators
- u2 = Number of Distinct Operands
- n2 = Total Number of Operands
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| calcLevel :: Int -> Int -> Int -> Float |
Calculates the Halstead Program Level
Halstead Program Level is calculated by the following formula:
(2 / u1) * (u2 / n2)Ê where
- u1 = Number of Distinct Operators
- u2 = Number of Distinct Operands
- n2 = Total Number of Operands
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| Auxiliary functions |
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| log2 :: Floating a => a -> a |
| Helper function that calculates the log2 of a floating point number |
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| Produced by Haddock version 0.6 |
