add a simple benchmark for f-strings

Demos/benchmarks/fstrings.py

+# coding=utf-8
+# NOTE: requires Python 3.6 or later if not compiled with Cython
+
+from time import time
+
+import cython
+
+
+@cython.locals(x=int, n=int)
+def run():
+    t0 = time()
+
+    f = 1.0
+    x = 2
+    n = 5
+    s = 'abc'
+    u = u'üöä'
+
+    for i in range(100):
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+        f"{n}oo{n*10}{f:.2}--{n:2}{n:5}oo{i}"
+
+        f"{n}oo{n*10}{f:3.2}--{n:2}{n:5}oo{i}{s}"
+        f"{n}oo{n*10}{f:5.2}--{n:2}{n:5}oo{i}{u}"
+        f"{n}oo{n*10}{f:2.2}--{n:2}{n:5}oo{i}{s}xx{u}"
+
+    tk = time()
+    return tk - t0
+
+
+def main(n):
+    run()  # warmup
+    times = []
+    for i in range(n):
+        times.append(run())
+    return times
+
+
+if __name__ == "__main__":
+    import optparse
+    import util
+    parser = optparse.OptionParser(
+        usage="%prog [options]",
+        description="Test the performance of fstring literal formatting")
+    util.add_standard_options_to(parser)
+    options, args = parser.parse_args()
+
+    util.run_benchmark(options, options.num_runs, main)