seq: Add seq.py and test script

Author: Expertcoderz

tests/seq.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env sh
+
+set -eux
+
+set -- \
+  '10' \
+  '5 10' \
+  '0 2 10' \
+  '1.35 0.05 2' \
+  '-- -1.0 2' \
+  '-- -1 2.5 3'
+
+for args in "$@"; do
+  test "$(python -m userland seq ${args})" = "$(seq ${args})"
+  test "$(python -m userland seq -w ${args})" = "$(seq -w ${args})"
+done
+
+exit 0

userland/utilities/seq.py

@@ -0,0 +1,98 @@
+import math
+import sys
+from decimal import Decimal, InvalidOperation
+
+from .. import core
+
+
+parser = core.create_parser(
+    usage=(
+        "%prog [OPTION]... LAST",
+        "%prog [OPTION]... FIRST LAST",
+        "%prog [OPTION]... FIRST INCREMENT LAST",
+    ),
+    description="Print numbers from FIRST to LAST, stepping by INCREMENT.",
+)
+
+parser.add_option(
+    "-f",
+    "--format",
+    metavar="FORMAT",
+    help="format numbers with printf-style FORMAT",
+)
+parser.add_option(
+    "-s",
+    "--separator",
+    default="\n",
+    metavar="STRING",
+    help="delimit outputs with STRING instead of newline",
+)
+parser.add_option(
+    "-w",
+    "--equal-width",
+    action="store_true",
+    help="pad with leading zeros to ensure equal width",
+)
+
+
+@core.command(parser)
+def python_userland_seq(opts, args):
+    if not args:
+        parser.error("missing operand")
+
+    if opts.format and opts.equal_width:
+        parser.error("--format and --equal-width are mutually exclusive")
+
+    def arg_to_decimal(arg: str) -> Decimal:
+        try:
+            return Decimal(
+                arg,
+            )
+        except InvalidOperation:
+            print(f"invalid decimal argument: {arg}", file=sys.stderr)
+            sys.exit(1)
+
+    if len(args) == 1:
+        first = Decimal(1)
+        increment = Decimal(1)
+        last = arg_to_decimal(args[0])
+        exponent = 0
+    elif len(args) == 2:
+        first = arg_to_decimal(args[0])
+        exponent = first.as_tuple().exponent
+        increment = Decimal(1)
+        last = arg_to_decimal(args[1]).quantize(first)
+    else:
+        first = arg_to_decimal(args[0])
+        increment = arg_to_decimal(args[1])
+        exponent = min(first.as_tuple().exponent, increment.as_tuple().exponent)
+        last = arg_to_decimal(args[2]).quantize(
+            first
+            if first.as_tuple().exponent < increment.as_tuple().exponent
+            else increment
+        )
+
+    formatstr: str
+
+    if opts.equal_width:
+        padding = math.floor(math.log10(last))
+        padding += -exponent + 2 if exponent else 1
+        if first < 0 or last < 0:
+            padding += 1
+
+        formatstr = f"%0{padding}.{-exponent}f" if exponent else f"%0{padding}g"
+    elif opts.format:
+        formatstr = opts.format
+    else:
+        formatstr = f"%.{-exponent}f" if exponent else "%g"
+
+    scale = 10**-exponent
+
+    print(formatstr % first, end="")
+    for i in range(
+        int((first + increment) * scale), int(last * scale) + 1, int(increment * scale)
+    ):
+        print(opts.separator + formatstr % (i / scale), end="")
+    print()
+
+    return 0