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Basic formatted I/O library plus one support lib.

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SVN=113977
This commit is contained in:
Rob Pike 2008-03-27 00:06:21 -07:00
parent d79b17e60a
commit 42d7850608
2 changed files with 500 additions and 0 deletions
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484
src/lib/fmt.go Normal file
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package fmt
/*
f := fmt.New();
print f.d(1234).s("\n").str(); // create string, print it
f.d(-1234).s("\n").put(); // print string
f.ud(^0).putnl(); // print string with automatic newline
*/
import sys "sys"
export Fmt, New;
var ldigits [16]byte; // BUG: should be constants
var udigits [16]byte; // BUG: can they be strings? looks like trouble with buf[i] = digits[val];
var inited bool;
var pows10 [160] double;
type Fmt struct {
buf string;
wid int;
wid_present bool;
prec int;
prec_present bool;
}
func (f *Fmt) clearflags() {
f.wid_present = false;
f.prec_present = false;
}
func (f *Fmt) clearbuf() {
f.buf = "";
}
func (f *Fmt) init() {
f.clearbuf();
f.clearflags();
if inited {
return;
}
var i byte;
for i = 0; i < 10; i++ {
ldigits[i] = '0' + i;
udigits[i] = '0' + i;
}
for i = 0; i < 6; i++ {
ldigits[i+10] = 'a' + i;
udigits[i+10] = 'A' + i;
}
// BUG: should be done with initialization
var p double = 1.0;
for i = 0; i < 160; i++ { // BUG: len(pows10)
pows10[i] = p;
p *= 10.0;
}
inited = true;
}
func New() *Fmt {
f := new(Fmt);
f.init();
return f;
}
func (f *Fmt) str() string {
s := f.buf;
f.clearbuf();
f.clearflags();
f.buf = "";
return s;
}
func (f *Fmt) put() {
print f.buf;
f.clearbuf();
f.clearflags();
}
func (f *Fmt) putnl() {
print f.buf, "\n";
f.clearbuf();
f.clearflags();
}
func (f *Fmt) wp(w, p int) *Fmt {
f.wid_present = true;
f.wid = w;
f.prec_present = true;
f.prec = p;
return f;
}
func (f *Fmt) p(p int) *Fmt {
f.prec_present = true;
f.prec = p;
return f;
}
func (f *Fmt) w(x int) *Fmt {
f.wid_present = true;
f.wid = x;
return f;
}
// append s to buf, padded on left (w > 0) or right (w < 0)
// padding is in bytes, not characters (agrees with ANSIC C, not Plan 9 C)
func (f *Fmt) pad(s string) {
if f.wid_present && f.wid != 0 {
left := true;
w := f.wid;
if w < 0 {
left = false;
w = -w;
}
w -= len(s);
if w > 0 {
if w > 64 { // BUG: should be able to use a const
w = 64;
}
var buf[64] byte; // BUG: should be able to allocate a size
for i := 0; i < w; i++ {
buf[i] = ' ';
}
if left {
s = string(buf)[0:w] + s;
} else {
s = s + string(buf)[0:w];
}
}
}
f.buf = f.buf + s; // BUG: += should work
}
// format val into buf, ending at buf[i]. (printing is easier right-to-left;
// that's why the bidi languages are right-to-left except for numbers. wait,
// never mind.) val is known to be unsigned. we could make things maybe
// marginally faster by splitting the 32-bit case out into a separate function
// but it's not worth the duplication, so val has 64 bits.
func putint(buf *[64]byte, i int, base, val uint64, digits *[16]byte) int {
for val >= base {
buf[i] = digits[val%base];
i--;
val /= base;
}
buf[i] = digits[val];
return i-1;
}
// integer; interprets prec but not wid.
func (f *Fmt) integer(a int64, base uint, is_signed bool, digits *[16]byte) string {
var buf [64]byte;
negative := is_signed && a < 0;
if negative {
a = -a;
}
i := putint(&buf, 63, uint64(base), uint64(a), digits);
if f.prec_present {
for i > 0 && f.prec > (63-i) {
buf[i] = '0';
i--;
}
}
if negative {
buf[i] = '-';
i--;
}
return string(buf)[i+1:64];
}
// decimal
func (f *Fmt) d(a int32) *Fmt {
f.pad(f.integer(int64(a), 10, true, &ldigits));
f.clearflags();
return f;
}
func (f *Fmt) D(a int64) *Fmt {
f.pad(f.integer(a, 10, true, &ldigits));
f.clearflags();
return f;
}
// unsigned decimal
func (f *Fmt) ud(a int32) *Fmt {
f.pad(f.integer(int64(uint32(a)), 10, false, &ldigits));
f.clearflags();
return f;
}
func (f *Fmt) uD(a int64) *Fmt {
f.pad(f.integer(a, 10, false, &ldigits));
f.clearflags();
return f;
}
// hexdecimal
func (f *Fmt) x(a int32) *Fmt {
f.pad(f.integer(int64(a), 16, true, &ldigits));
f.clearflags();
return f;
}
func (f *Fmt) X(a int64) *Fmt {
f.pad(f.integer(a, 16, true, &ldigits));
f.clearflags();
return f;
}
// unsigned hexdecimal
func (f *Fmt) ux(a int32) *Fmt {
f.pad(f.integer(int64(uint32(a)), 16, false, &ldigits));
f.clearflags();
return f;
}
func (f *Fmt) uX(a int64) *Fmt {
f.pad(f.integer(a, 16, false, &ldigits));
f.clearflags();
return f;
}
// HEXADECIMAL
func (f *Fmt) Ux(a int32) *Fmt {
f.pad(f.integer(int64(a), 16, true, &udigits));
f.clearflags();
return f;
}
func (f *Fmt) UX(a int64) *Fmt {
f.pad(f.integer(a, 16, true, &udigits));
f.clearflags();
return f;
}
// unsigned HEXADECIMAL
func (f *Fmt) uUx(a int32) *Fmt {
f.pad(f.integer(int64(uint32(a)), 16, false, &udigits));
f.clearflags();
return f;
}
func (f *Fmt) uUX(a int64) *Fmt {
f.pad(f.integer(a, 16, false, &udigits));
f.clearflags();
return f;
}
// octal
func (f *Fmt) o(a int32) *Fmt {
f.pad(f.integer(int64(a), 8, true, &ldigits));
f.clearflags();
return f;
}
func (f *Fmt) O(a int64) *Fmt {
f.pad(f.integer(a, 8, true, &ldigits));
f.clearflags();
return f;
}
// unsigned octal
func (f *Fmt) uo(a int32) *Fmt {
f.pad(f.integer(int64(uint32(a)), 8, false, &ldigits));
f.clearflags();
return f;
}
func (f *Fmt) uO(a int64) *Fmt {
f.pad(f.integer(a, 8, false, &ldigits));
f.clearflags();
return f;
}
// binary
func (f *Fmt) b(a int32) *Fmt {
f.pad(f.integer(int64(uint32(a)), 2, false, &ldigits));
f.clearflags();
return f;
}
func (f *Fmt) B(a int64) *Fmt {
f.pad(f.integer(a, 2, false, &ldigits));
f.clearflags();
return f;
}
// character
func (f *Fmt) c(a int) *Fmt {
f.pad(string(a));
f.clearflags();
return f;
}
// string
func (f *Fmt) s(s string) *Fmt {
if f.prec_present {
if f.prec < len(s) {
w := f.prec; // BUG: can't use f.prec in slice
s = s[0:w];
}
}
f.pad(s);
f.clearflags();
return f;
}
func pow10(n int) double {
var d double;
npows10 := 160; // nelem(pows10); BUG: why not a const?
neg := false;
if n < 0 {
if n < -307 { // DBL_MIN_10_EXP
return 0.;
}
neg = true;
n = -n;
}else if n > 308 { // DBL_MAX_10_EXP
return 1.79769e+308; // HUGE_VAL
}
if n < npows10 {
d = pows10[n];
} else {
d = pows10[npows10-1];
for {
n -= npows10 - 1;
if n < npows10 {
d *= pows10[n];
break;
}
d *= pows10[npows10 - 1];
}
}
if neg {
return 1/d;
}
return d;
}
func unpack(a double) (negative bool, exp int, num double) {
neg := a < 0;
if neg {
a = -a;
}
// find g,e such that a = g*10^e.
// guess 10-exponent using 2-exponent, then fine tune.
var g double;
var e2 int;
e2, g = sys.frexp(a);
e := int(e2 * .301029995663981);
g := a * pow10(-e);
for g < 1 {
e--;
g = a * pow10(-e);
}
for g >= 10 {
e++;
g = a * pow10(-e);
}
return neg, e, g;
}
// double
func (f *Fmt) E(a double) *Fmt {
var negative bool;
var g double;
var exp int;
negative, exp, g = unpack(a);
prec := 6;
if f.prec_present {
prec = f.prec;
}
prec++; // one digit left of decimal
// multiply by 10^prec to get decimal places; put decimal after first digit
g *= pow10(prec);
s := f.integer(int64(g + .5), 10, true, &ldigits); // get the digits into a string
s = s[0:1] + "." + s[1:prec]; // insert a decimal point
// print exponent with leading 0 if appropriate.
es := New().p(2).integer(int64(exp), 10, true, &ldigits);
if exp > 0 {
es = "+" + es; // BUG: should do this with a fmt flag
}
s = s + "e" + es;
if negative {
s = "-" + s;
}
f.pad(s);
f.clearflags();
return f;
}
// double
func (f *Fmt) F(a double) *Fmt {
var negative bool;
var g double;
var exp int;
negative, exp, g = unpack(a);
if exp > 19 || exp < -19 { // too big for this sloppy code
return f.E(a);
}
prec := 6;
if f.prec_present {
prec = f.prec;
}
// prec is number of digits after decimal point
s := "NO";
if exp >= 0 {
g *= pow10(exp);
gi := int64(g);
s = New().integer(gi, 10, true, &ldigits);
s = s + ".";
g -= double(gi);
s = s + New().p(prec).integer(int64(g*pow10(prec) + .5), 10, true, &ldigits);
} else {
g *= pow10(prec + exp);
s = "0." + New().p(prec).integer(int64(g + .5), 10, true, &ldigits);
}
if negative {
s = "-" + s;
}
f.pad(s);
f.clearflags();
return f;
}
// double
func (f *Fmt) G(a double) *Fmt {
f1 := New();
f2 := New();
if f.wid_present {
f1.w(f.wid);
f2.w(f.wid);
}
if f.prec_present {
f1.p(f.prec);
f2.p(f.prec);
}
efmt := f1.E(a).str();
ffmt := f2.F(a).str();
// ffmt can return e in my bogus world; don't trim trailing 0s if so.
f_is_e := false;
for i := 0; i < len(ffmt); i++ {
if ffmt[i] == 'e' {
f_is_e = true;
break;
}
}
if !f_is_e {
// strip trailing zeros
l := len(ffmt);
for ffmt[l-1]=='0' {
l--;
}
ffmt = ffmt[0:l];
}
if len(efmt) < len(ffmt) {
f.pad(efmt);
} else {
f.pad(ffmt);
}
f.clearflags();
return f;
}
// float
func (x *Fmt) f(a float) *Fmt {
return x.F(double(a));
}
// float
func (x *Fmt) e(a float) *Fmt {
return x.E(double(a));
}
// float
func (x *Fmt) g(a float) *Fmt {
return x.G(double(a));
}

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src/lib/sys.go Normal file
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package sys
func modf(a double) (double, double);
func frexp(a double) (int, double);
func ldexp(double, int) double;
func Inf(n int) double;
func NaN() double;
func isInf(arg double, n int) bool;
export modf, frexp, ldexp
export NaN, isInf, Inf