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51 lines
1.3 KiB
51 lines
1.3 KiB
3 years ago
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// Copyright 2009 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 jx
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import (
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"math"
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"strconv"
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)
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// Float writes float value to buffer.
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func (w *Writer) Float(v float64, bits int) {
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if math.IsNaN(v) || math.IsInf(v, 0) {
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// Like in ECMA:
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// NaN and Infinity regardless of sign are represented
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// as the String null.
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//
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// JSON.stringify({"foo":NaN}) -> {"foo":null}
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w.Null()
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return
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}
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// From go std sources, strconv/ftoa.go:
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// Convert as if by ES6 number to string conversion.
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// This matches most other JSON generators.
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// See golang.org/issue/6384 and golang.org/issue/14135.
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// Like fmt %g, but the exponent cutoffs are different
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// and exponents themselves are not padded to two digits.
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b := w.Buf
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abs := math.Abs(v)
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fmt := byte('f')
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// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
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if abs != 0 {
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if bits == 64 && (abs < 1e-6 || abs >= 1e21) || bits == 32 && (float32(abs) < 1e-6 || float32(abs) >= 1e21) {
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fmt = 'e'
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}
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}
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b = strconv.AppendFloat(b, v, fmt, -1, bits)
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if fmt == 'e' {
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// clean up e-09 to e-9
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n := len(b)
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if n >= 4 && b[n-4] == 'e' && b[n-3] == '-' && b[n-2] == '0' {
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b[n-2] = b[n-1]
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b = b[:n-1]
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}
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}
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w.Buf = b
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}
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