making jython-2.1 available for scripting

1 files changed, 142 insertions, 0 deletions

diff --git a/lib/jython/Lib/fpformat.py b/lib/jython/Lib/fpformat.py
new file mode 100644
index 000000000..21d2489ec
--- /dev/null
+++ b/lib/jython/Lib/fpformat.py
@@ -0,0 +1,142 @@
+"""General floating point formatting functions.

+

+Functions:

+fix(x, digits_behind)

+sci(x, digits_behind)

+

+Each takes a number or a string and a number of digits as arguments.

+

+Parameters:

+x:             number to be formatted; or a string resembling a number

+digits_behind: number of digits behind the decimal point

+"""

+

+import re

+

+__all__ = ["fix","sci","NotANumber"]

+

+# Compiled regular expression to "decode" a number

+decoder = re.compile(r'^([-+]?)0*(\d*)((?:\.\d*)?)(([eE][-+]?\d+)?)$')

+# \0 the whole thing

+# \1 leading sign or empty

+# \2 digits left of decimal point

+# \3 fraction (empty or begins with point)

+# \4 exponent part (empty or begins with 'e' or 'E')

+

+try:

+    class NotANumber(ValueError):

+        pass

+except TypeError:

+    NotANumber = 'fpformat.NotANumber'

+

+def extract(s):

+    """Return (sign, intpart, fraction, expo) or raise an exception:

+    sign is '+' or '-'

+    intpart is 0 or more digits beginning with a nonzero

+    fraction is 0 or more digits

+    expo is an integer"""

+    res = decoder.match(s)

+    if res is None: raise NotANumber, s

+    sign, intpart, fraction, exppart = res.group(1,2,3,4)

+    if sign == '+': sign = ''

+    if fraction: fraction = fraction[1:]

+    if exppart: expo = int(exppart[1:])

+    else: expo = 0

+    return sign, intpart, fraction, expo

+

+def unexpo(intpart, fraction, expo):

+    """Remove the exponent by changing intpart and fraction."""

+    if expo > 0: # Move the point left

+        f = len(fraction)

+        intpart, fraction = intpart + fraction[:expo], fraction[expo:]

+        if expo > f:

+            intpart = intpart + '0'*(expo-f)

+    elif expo < 0: # Move the point right

+        i = len(intpart)

+        intpart, fraction = intpart[:expo], intpart[expo:] + fraction

+        if expo < -i:

+            fraction = '0'*(-expo-i) + fraction

+    return intpart, fraction

+

+def roundfrac(intpart, fraction, digs):

+    """Round or extend the fraction to size digs."""

+    f = len(fraction)

+    if f <= digs:

+        return intpart, fraction + '0'*(digs-f)

+    i = len(intpart)

+    if i+digs < 0:

+        return '0'*-digs, ''

+    total = intpart + fraction

+    nextdigit = total[i+digs]

+    if nextdigit >= '5': # Hard case: increment last digit, may have carry!

+        n = i + digs - 1

+        while n >= 0:

+            if total[n] != '9': break

+            n = n-1

+        else:

+            total = '0' + total

+            i = i+1

+            n = 0

+        total = total[:n] + chr(ord(total[n]) + 1) + '0'*(len(total)-n-1)

+        intpart, fraction = total[:i], total[i:]

+    if digs >= 0:

+        return intpart, fraction[:digs]

+    else:

+        return intpart[:digs] + '0'*-digs, ''

+

+def fix(x, digs):

+    """Format x as [-]ddd.ddd with 'digs' digits after the point

+    and at least one digit before.

+    If digs <= 0, the point is suppressed."""

+    if type(x) != type(''): x = `x`

+    try:

+        sign, intpart, fraction, expo = extract(x)

+    except NotANumber:

+        return x

+    intpart, fraction = unexpo(intpart, fraction, expo)

+    intpart, fraction = roundfrac(intpart, fraction, digs)

+    while intpart and intpart[0] == '0': intpart = intpart[1:]

+    if intpart == '': intpart = '0'

+    if digs > 0: return sign + intpart + '.' + fraction

+    else: return sign + intpart

+

+def sci(x, digs):

+    """Format x as [-]d.dddE[+-]ddd with 'digs' digits after the point

+    and exactly one digit before.

+    If digs is <= 0, one digit is kept and the point is suppressed."""

+    if type(x) != type(''): x = `x`

+    sign, intpart, fraction, expo = extract(x)

+    if not intpart:

+        while fraction and fraction[0] == '0':

+            fraction = fraction[1:]

+            expo = expo - 1

+        if fraction:

+            intpart, fraction = fraction[0], fraction[1:]

+            expo = expo - 1

+        else:

+            intpart = '0'

+    else:

+        expo = expo + len(intpart) - 1

+        intpart, fraction = intpart[0], intpart[1:] + fraction

+    digs = max(0, digs)

+    intpart, fraction = roundfrac(intpart, fraction, digs)

+    if len(intpart) > 1:

+        intpart, fraction, expo = \

+            intpart[0], intpart[1:] + fraction[:-1], \

+            expo + len(intpart) - 1

+    s = sign + intpart

+    if digs > 0: s = s + '.' + fraction

+    e = `abs(expo)`

+    e = '0'*(3-len(e)) + e

+    if expo < 0: e = '-' + e

+    else: e = '+' + e

+    return s + 'e' + e

+

+def test():

+    """Interactive test run."""

+    try:

+        while 1:

+            x, digs = input('Enter (x, digs): ')

+            print x, fix(x, digs), sci(x, digs)

+    except (EOFError, KeyboardInterrupt):

+        pass