mirror of
https://github.com/golang/go
synced 2024-11-11 23:10:23 -07:00
strconv: add ParseComplex and FormatComplex
Adds two functions to deal with complex numbers:
* FormatComplex
* ParseComplex
ParseComplex accepts complex numbers in this format: N+Ni
Fixes #36771
Change-Id: Id184dc9e277e5fa01a714ad656a88255ead05085
GitHub-Last-Rev: 036a075d36
GitHub-Pull-Request: golang/go#36815
Reviewed-on: https://go-review.googlesource.com/c/go/+/216617
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
pj
Robert Griesemer
parent
55361a2617
commit
4f65fb3b30
105
src/strconv/atoc.go
Normal file
105
src/strconv/atoc.go
Normal file
@ -0,0 +1,105 @@
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// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package strconv
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const fnParseComplex = "ParseComplex"
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// convErr splits an error returned by parseFloatPrefix
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// into a syntax or range error for ParseComplex.
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func convErr(err error, s string) (syntax, range_ error) {
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if x, ok := err.(*NumError); ok {
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x.Func = fnParseComplex
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x.Num = s
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if x.Err == ErrRange {
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return nil, x
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}
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}
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return err, nil
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}
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// ParseComplex converts the string s to a complex number
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// with the precision specified by bitSize: 64 for complex64, or 128 for complex128.
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// When bitSize=64, the result still has type complex128, but it will be
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// convertible to complex64 without changing its value.
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//
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// The number represented by s must be of the form N, Ni, or N±Ni, where N stands
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// for a floating-point number as recognized by ParseFloat, and i is the imaginary
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// component. If the second N is unsigned, a + sign is required between the two components
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// as indicated by the ±. If the second N is NaN, only a + sign is accepted.
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// The form may be parenthesized and cannot contain any spaces.
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// The resulting complex number consists of the two components converted by ParseFloat.
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//
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// The errors that ParseComplex returns have concrete type *NumError
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// and include err.Num = s.
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//
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// If s is not syntactically well-formed, ParseComplex returns err.Err = ErrSyntax.
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//
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// If s is syntactically well-formed but either component is more than 1/2 ULP
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// away from the largest floating point number of the given component's size,
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// ParseComplex returns err.Err = ErrRange and c = ±Inf for the respective component.
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func ParseComplex(s string, bitSize int) (complex128, error) {
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size := 128
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if bitSize == 64 {
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size = 32 // complex64 uses float32 parts
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}
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orig := s
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// Remove parentheses, if any.
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if len(s) >= 2 && s[0] == '(' && s[len(s)-1] == ')' {
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s = s[1 : len(s)-1]
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}
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var pending error // pending range error, or nil
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// Read real part (possibly imaginary part if followed by 'i').
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re, n, err := parseFloatPrefix(s, size)
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if err != nil {
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err, pending = convErr(err, orig)
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if err != nil {
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return 0, err
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}
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}
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s = s[n:]
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// If we have nothing left, we're done.
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if len(s) == 0 {
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return complex(re, 0), pending
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}
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// Otherwise, look at the next character.
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switch s[0] {
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case '+':
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// Consume the '+' to avoid an error if we have "+NaNi", but
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// do this only if we don't have a "++" (don't hide that error).
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if len(s) > 1 && s[1] != '+' {
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s = s[1:]
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}
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case '-':
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// ok
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case 'i':
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// If 'i' is the last character, we only have an imaginary part.
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if len(s) == 1 {
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return complex(0, re), pending
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}
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fallthrough
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default:
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return 0, syntaxError(fnParseComplex, orig)
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}
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// Read imaginary part.
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im, n, err := parseFloatPrefix(s, size)
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if err != nil {
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err, pending = convErr(err, orig)
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if err != nil {
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return 0, err
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}
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}
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s = s[n:]
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if s != "i" {
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return 0, syntaxError(fnParseComplex, orig)
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}
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return complex(re, im), pending
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}
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195
src/strconv/atoc_test.go
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195
src/strconv/atoc_test.go
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@ -0,0 +1,195 @@
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// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package strconv_test
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import (
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"math"
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"math/cmplx"
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"reflect"
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. "strconv"
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"testing"
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)
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var (
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infp0 = complex(math.Inf(+1), 0)
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infm0 = complex(math.Inf(-1), 0)
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inf0p = complex(0, math.Inf(+1))
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inf0m = complex(0, math.Inf(-1))
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infpp = complex(math.Inf(+1), math.Inf(+1))
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infpm = complex(math.Inf(+1), math.Inf(-1))
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infmp = complex(math.Inf(-1), math.Inf(+1))
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infmm = complex(math.Inf(-1), math.Inf(-1))
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)
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type atocTest struct {
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in string
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out complex128
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err error
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}
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func TestParseComplex(t *testing.T) {
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tests := []atocTest{
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// Clearly invalid
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{"", 0, ErrSyntax},
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{" ", 0, ErrSyntax},
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{"(", 0, ErrSyntax},
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{")", 0, ErrSyntax},
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{"i", 0, ErrSyntax},
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{"+i", 0, ErrSyntax},
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{"-i", 0, ErrSyntax},
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{"1I", 0, ErrSyntax},
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{"10 + 5i", 0, ErrSyntax},
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{"3+", 0, ErrSyntax},
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{"3+5", 0, ErrSyntax},
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{"3+5+5i", 0, ErrSyntax},
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// Parentheses
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{"()", 0, ErrSyntax},
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{"(i)", 0, ErrSyntax},
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{"(0)", 0, nil},
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{"(1i)", 1i, nil},
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{"(3.0+5.5i)", 3.0 + 5.5i, nil},
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{"(1)+1i", 0, ErrSyntax},
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{"(3.0+5.5i", 0, ErrSyntax},
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{"3.0+5.5i)", 0, ErrSyntax},
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// NaNs
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{"NaN", complex(math.NaN(), 0), nil},
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{"NANi", complex(0, math.NaN()), nil},
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{"nan+nAni", complex(math.NaN(), math.NaN()), nil},
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{"+NaN", 0, ErrSyntax},
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{"-NaN", 0, ErrSyntax},
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{"NaN-NaNi", 0, ErrSyntax},
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// Infs
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{"Inf", infp0, nil},
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{"+inf", infp0, nil},
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{"-inf", infm0, nil},
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{"Infinity", infp0, nil},
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{"+INFINITY", infp0, nil},
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{"-infinity", infm0, nil},
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{"+infi", inf0p, nil},
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{"0-infinityi", inf0m, nil},
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{"Inf+Infi", infpp, nil},
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{"+Inf-Infi", infpm, nil},
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{"-Infinity+Infi", infmp, nil},
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{"inf-inf", 0, ErrSyntax},
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// Zeros
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{"0", 0, nil},
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{"0i", 0, nil},
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{"-0.0i", 0, nil},
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{"0+0.0i", 0, nil},
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{"0e+0i", 0, nil},
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{"0e-0+0i", 0, nil},
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{"-0.0-0.0i", 0, nil},
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{"0e+012345", 0, nil},
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{"0x0p+012345i", 0, nil},
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{"0x0.00p-012345i", 0, nil},
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{"+0e-0+0e-0i", 0, nil},
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{"0e+0+0e+0i", 0, nil},
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{"-0e+0-0e+0i", 0, nil},
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// Regular non-zeroes
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{"0.1", 0.1, nil},
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{"0.1i", 0 + 0.1i, nil},
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{"0.123", 0.123, nil},
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{"0.123i", 0 + 0.123i, nil},
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{"0.123+0.123i", 0.123 + 0.123i, nil},
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{"99", 99, nil},
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{"+99", 99, nil},
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{"-99", -99, nil},
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{"+1i", 1i, nil},
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{"-1i", -1i, nil},
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{"+3+1i", 3 + 1i, nil},
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{"30+3i", 30 + 3i, nil},
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{"+3e+3-3e+3i", 3e+3 - 3e+3i, nil},
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{"+3e+3+3e+3i", 3e+3 + 3e+3i, nil},
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{"+3e+3+3e+3i+", 0, ErrSyntax},
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// Separators
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{"0.1", 0.1, nil},
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{"0.1i", 0 + 0.1i, nil},
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{"0.1_2_3", 0.123, nil},
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{"+0x_3p3i", 0x3p3i, nil},
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{"0x_10.3p-8+0x3p3i", 0x10.3p-8 + 0x3p3i, nil},
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{"+0x_1_0.3p-8+0x3p3i", 0x10.3p-8 + 0x3p3i, nil},
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{"0x10.3p+8-0x_3p3i", 0x10.3p+8 - 0x3p3i, nil},
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// Hexadecimals
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{"0x10.3p-8+0x3p3i", 0x10.3p-8 + 0x3p3i, nil},
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{"+0x10.3p-8+0x3p3i", 0x10.3p-8 + 0x3p3i, nil},
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{"0x10.3p+8-0x3p3i", 0x10.3p+8 - 0x3p3i, nil},
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{"0x1p0", 1, nil},
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{"0x1p1", 2, nil},
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{"0x1p-1", 0.5, nil},
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{"0x1ep-1", 15, nil},
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{"-0x1ep-1", -15, nil},
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{"-0x2p3", -16, nil},
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{"0x1e2", 0, ErrSyntax},
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{"1p2", 0, ErrSyntax},
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{"0x1e2i", 0, ErrSyntax},
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// ErrRange
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// next float64 - too large
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{"+0x1p1024", infp0, ErrRange},
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{"-0x1p1024", infm0, ErrRange},
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{"+0x1p1024i", inf0p, ErrRange},
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{"-0x1p1024i", inf0m, ErrRange},
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{"+0x1p1024+0x1p1024i", infpp, ErrRange},
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{"+0x1p1024-0x1p1024i", infpm, ErrRange},
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{"-0x1p1024+0x1p1024i", infmp, ErrRange},
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{"-0x1p1024-0x1p1024i", infmm, ErrRange},
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// the border is ...158079
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// borderline - okay
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{"+0x1.fffffffffffff7fffp1023+0x1.fffffffffffff7fffp1023i", 1.7976931348623157e+308 + 1.7976931348623157e+308i, nil},
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{"+0x1.fffffffffffff7fffp1023-0x1.fffffffffffff7fffp1023i", 1.7976931348623157e+308 - 1.7976931348623157e+308i, nil},
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{"-0x1.fffffffffffff7fffp1023+0x1.fffffffffffff7fffp1023i", -1.7976931348623157e+308 + 1.7976931348623157e+308i, nil},
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{"-0x1.fffffffffffff7fffp1023-0x1.fffffffffffff7fffp1023i", -1.7976931348623157e+308 - 1.7976931348623157e+308i, nil},
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// borderline - too large
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{"+0x1.fffffffffffff8p1023", infp0, ErrRange},
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{"-0x1fffffffffffff.8p+971", infm0, ErrRange},
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{"+0x1.fffffffffffff8p1023i", inf0p, ErrRange},
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{"-0x1fffffffffffff.8p+971i", inf0m, ErrRange},
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{"+0x1.fffffffffffff8p1023+0x1.fffffffffffff8p1023i", infpp, ErrRange},
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{"+0x1.fffffffffffff8p1023-0x1.fffffffffffff8p1023i", infpm, ErrRange},
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{"-0x1fffffffffffff.8p+971+0x1fffffffffffff.8p+971i", infmp, ErrRange},
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{"-0x1fffffffffffff8p+967-0x1fffffffffffff8p+967i", infmm, ErrRange},
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// a little too large
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{"1e308+1e308i", 1e+308 + 1e+308i, nil},
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{"2e308+2e308i", infpp, ErrRange},
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{"1e309+1e309i", infpp, ErrRange},
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{"0x1p1025+0x1p1025i", infpp, ErrRange},
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{"2e308", infp0, ErrRange},
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{"1e309", infp0, ErrRange},
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{"0x1p1025", infp0, ErrRange},
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{"2e308i", inf0p, ErrRange},
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{"1e309i", inf0p, ErrRange},
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{"0x1p1025i", inf0p, ErrRange},
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// way too large
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{"+1e310+1e310i", infpp, ErrRange},
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{"+1e310-1e310i", infpm, ErrRange},
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{"-1e310+1e310i", infmp, ErrRange},
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{"-1e310-1e310i", infmm, ErrRange},
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// under/overflow exponent
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{"1e-4294967296", 0, nil},
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{"1e-4294967296i", 0, nil},
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{"1e-4294967296+1i", 1i, nil},
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{"1+1e-4294967296i", 1, nil},
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{"1e-4294967296+1e-4294967296i", 0, nil},
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{"1e+4294967296", infp0, ErrRange},
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{"1e+4294967296i", inf0p, ErrRange},
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{"1e+4294967296+1e+4294967296i", infpp, ErrRange},
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{"1e+4294967296-1e+4294967296i", infpm, ErrRange},
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}
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for _, tt := range tests {
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tt := tt // for capture in Run closures below
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if tt.err != nil {
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tt.err = &NumError{Func: "ParseComplex", Num: tt.in, Err: tt.err}
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}
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t.Run(tt.in, func(t *testing.T) {
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got, err := ParseComplex(tt.in, 128)
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if !reflect.DeepEqual(err, tt.err) {
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t.Fatalf("ParseComplex(%q, 128) = %v, %v want %v, %v", tt.in, got, err, tt.out, tt.err)
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}
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if !(cmplx.IsNaN(tt.out) && cmplx.IsNaN(got)) && got != tt.out {
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t.Fatalf("ParseComplex(%q, 128) = %v, %v want %v, %v", tt.in, got, err, tt.out, tt.err)
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}
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})
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}
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}
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@ -677,8 +677,8 @@ func atof64(s string) (f float64, n int, err error) {
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// away from the largest floating point number of the given size,
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// ParseFloat returns f = ±Inf, err.Err = ErrRange.
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//
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// ParseFloat recognizes the strings "NaN", "+Inf", and "-Inf" as their
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// respective special floating point values. It ignores case when matching.
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// ParseFloat recognizes the strings "NaN", and the (possibly signed) strings "Inf" and "Infinity"
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// as their respective special floating point values. It ignores case when matching.
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func ParseFloat(s string, bitSize int) (float64, error) {
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f, n, err := parseFloatPrefix(s, bitSize)
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if err == nil && n != len(s) {
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@ -22,7 +22,7 @@ var ErrSyntax = errors.New("invalid syntax")
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// A NumError records a failed conversion.
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type NumError struct {
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Func string // the failing function (ParseBool, ParseInt, ParseUint, ParseFloat)
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Func string // the failing function (ParseBool, ParseInt, ParseUint, ParseFloat, ParseComplex)
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Num string // the input
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Err error // the reason the conversion failed (e.g. ErrRange, ErrSyntax, etc.)
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}
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27
src/strconv/ctoa.go
Normal file
27
src/strconv/ctoa.go
Normal file
@ -0,0 +1,27 @@
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// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package strconv
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// FormatComplex converts the complex number c to a string of the
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// form (a+bi) where a and b are the real and imaginary parts,
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// formatted according to the format fmt and precision prec.
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//
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// The format fmt and precision prec have the same meaning as in FormatFloat.
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// It rounds the result assuming that the original was obtained from a complex
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// value of bitSize bits, which must be 64 for complex64 and 128 for complex128.
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func FormatComplex(c complex128, fmt byte, prec, bitSize int) string {
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if bitSize != 64 && bitSize != 128 {
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panic("invalid bitSize")
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}
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bitSize >>= 1 // complex64 uses float32 internally
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// Check if imaginary part has a sign. If not, add one.
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im := FormatFloat(imag(c), fmt, prec, bitSize)
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if im[0] != '+' && im[0] != '-' {
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im = "+" + im
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}
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return "(" + FormatFloat(real(c), fmt, prec, bitSize) + im + "i)"
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}
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