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Diffstat (limited to 'common/math/math.go')
-rw-r--r-- | common/math/math.go | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/common/math/math.go b/common/math/math.go new file mode 100644 index 000000000..3c5ef1f9d --- /dev/null +++ b/common/math/math.go @@ -0,0 +1,135 @@ +// Copyright 2018 The Hugo Authors. All rights reserved. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package math + +import ( + "errors" + "reflect" +) + +// DoArithmetic performs arithmetic operations (+,-,*,/) using reflection to +// determine the type of the two terms. +func DoArithmetic(a, b interface{}, op rune) (interface{}, error) { + av := reflect.ValueOf(a) + bv := reflect.ValueOf(b) + var ai, bi int64 + var af, bf float64 + var au, bu uint64 + switch av.Kind() { + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + ai = av.Int() + switch bv.Kind() { + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + bi = bv.Int() + case reflect.Float32, reflect.Float64: + af = float64(ai) // may overflow + ai = 0 + bf = bv.Float() + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: + bu = bv.Uint() + if ai >= 0 { + au = uint64(ai) + ai = 0 + } else { + bi = int64(bu) // may overflow + bu = 0 + } + default: + return nil, errors.New("Can't apply the operator to the values") + } + case reflect.Float32, reflect.Float64: + af = av.Float() + switch bv.Kind() { + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + bf = float64(bv.Int()) // may overflow + case reflect.Float32, reflect.Float64: + bf = bv.Float() + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: + bf = float64(bv.Uint()) // may overflow + default: + return nil, errors.New("Can't apply the operator to the values") + } + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: + au = av.Uint() + switch bv.Kind() { + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + bi = bv.Int() + if bi >= 0 { + bu = uint64(bi) + bi = 0 + } else { + ai = int64(au) // may overflow + au = 0 + } + case reflect.Float32, reflect.Float64: + af = float64(au) // may overflow + au = 0 + bf = bv.Float() + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: + bu = bv.Uint() + default: + return nil, errors.New("Can't apply the operator to the values") + } + case reflect.String: + as := av.String() + if bv.Kind() == reflect.String && op == '+' { + bs := bv.String() + return as + bs, nil + } + return nil, errors.New("Can't apply the operator to the values") + default: + return nil, errors.New("Can't apply the operator to the values") + } + + switch op { + case '+': + if ai != 0 || bi != 0 { + return ai + bi, nil + } else if af != 0 || bf != 0 { + return af + bf, nil + } else if au != 0 || bu != 0 { + return au + bu, nil + } + return 0, nil + case '-': + if ai != 0 || bi != 0 { + return ai - bi, nil + } else if af != 0 || bf != 0 { + return af - bf, nil + } else if au != 0 || bu != 0 { + return au - bu, nil + } + return 0, nil + case '*': + if ai != 0 || bi != 0 { + return ai * bi, nil + } else if af != 0 || bf != 0 { + return af * bf, nil + } else if au != 0 || bu != 0 { + return au * bu, nil + } + return 0, nil + case '/': + if bi != 0 { + return ai / bi, nil + } else if bf != 0 { + return af / bf, nil + } else if bu != 0 { + return au / bu, nil + } + return nil, errors.New("Can't divide the value by 0") + default: + return nil, errors.New("There is no such an operation") + } +} |