Implement benchmarks for parsing

Relates to #62

Cargo.lock

@@ -8,6 +8,11 @@ dependencies = [
  "memchr 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "autocfg"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "base64"
 version = "0.10.1"
@@ -45,6 +50,7 @@ name = "evalexpr"
 version = "5.0.0-beta.1"
 dependencies = [
  "rand 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_pcg 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "ron 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.99 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -134,6 +140,15 @@ dependencies = [
  "rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "rand_pcg"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "autocfg 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "regex"
 version = "1.2.1"
@@ -208,6 +223,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [metadata]
 "checksum aho-corasick 0.7.6 (registry+https://github.com/rust-lang/crates.io-index)" = "58fb5e95d83b38284460a5fda7d6470aa0b8844d283a0b614b8535e880800d2d"
+"checksum autocfg 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "b671c8fb71b457dd4ae18c4ba1e59aa81793daacc361d82fcd410cef0d491875"
 "checksum base64 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0b25d992356d2eb0ed82172f5248873db5560c4721f564b13cb5193bda5e668e"
 "checksum bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3d155346769a6855b86399e9bc3814ab343cd3d62c7e985113d46a0ec3c281fd"
 "checksum byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "a7c3dd8985a7111efc5c80b44e23ecdd8c007de8ade3b96595387e812b957cf5"
@@ -224,6 +240,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum rand_chacha 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "03a2a90da8c7523f554344f921aa97283eadf6ac484a6d2a7d0212fa7f8d6853"
 "checksum rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "90bde5296fc891b0cef12a6d03ddccc162ce7b2aff54160af9338f8d40df6d19"
 "checksum rand_hc 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ca3129af7b92a17112d59ad498c6f81eaf463253766b90396d39ea7a39d6613c"
+"checksum rand_pcg 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3e196346cbbc5c70c77e7b4926147ee8e383a38ee4d15d58a08098b169e492b6"
 "checksum regex 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "88c3d9193984285d544df4a30c23a4e62ead42edf70a4452ceb76dac1ce05c26"
 "checksum regex-syntax 0.6.11 (registry+https://github.com/rust-lang/crates.io-index)" = "b143cceb2ca5e56d5671988ef8b15615733e7ee16cd348e064333b251b89343f"
 "checksum ron 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "17f52a24414403f81528b67488cf8edc4eda977d3af1646bb6b106a600ead78f"

Cargo.toml

@@ -27,3 +27,9 @@ regex_support = ["regex"]
 
 [dev-dependencies]
 ron = "0.4"
+rand = "0.7.0"
+rand_pcg = "0.2.0"
+
+[target.bench.dependencies]
+rand = "0.7.0"
+rand_pcg = "0.2.0"

benches/benchs.rs

@@ -0,0 +1,84 @@
+#![feature(test)]
+
+extern crate test;
+extern crate rand;
+extern crate rand_pcg;
+
+use test::Bencher;
+use rand_pcg::Pcg32;
+use rand::{Rng, SeedableRng};
+use rand::distributions::Uniform;
+use rand::seq::SliceRandom;
+use evalexpr::build_operator_tree;
+use std::hint::black_box;
+
+const BENCHMARK_LEN: usize = 100_000;
+
+fn generate_expression<Gen: Rng>(len: usize, gen: &mut Gen) -> String {
+    let int_distribution = Uniform::new_inclusive(-100, 100);
+    let whitespaces = vec![" ", "", "", "  ", " \n", "       "];
+    let operators = vec!["+", "-", "*", "/", "%", "^"];
+    let mut result = String::new();
+    result.push_str(&format!("{}", gen.sample(int_distribution)));
+
+    while result.len() < len {
+        result.push_str(whitespaces.choose(gen).unwrap());
+        result.push_str(operators.choose(gen).unwrap());
+        result.push_str(whitespaces.choose(gen).unwrap());
+        result.push_str(&format!("{}", gen.sample(int_distribution)));
+    }
+
+    result
+}
+
+fn generate_expression_chain<Gen: Rng>(len: usize, gen: &mut Gen) -> String {
+    let mut chain = generate_expression(10, gen);
+    while chain.len() < len {
+        chain.push_str("; ");
+        chain.push_str(&generate_expression(10, gen));
+    }
+    chain
+}
+
+fn generate_small_expressions<Gen: Rng>(len: usize, gen: &mut Gen) -> Vec<String> {
+    let mut result = Vec::new();
+    let mut result_len = 0;
+    while result_len < len {
+        let expression = generate_expression(10, gen);
+        result_len += expression.len();
+        result.push(expression);
+    }
+    result
+}
+
+#[bench]
+fn bench_parse_long_expression_chains(bencher: &mut Bencher) {
+    let mut gen = Pcg32::seed_from_u64(0);
+    let long_expression_chain = generate_expression_chain(BENCHMARK_LEN, &mut gen);
+
+    bencher.iter(|| {
+        build_operator_tree(&long_expression_chain).unwrap()
+    });
+}
+
+#[bench]
+fn bench_parse_deep_expression_trees(bencher: &mut Bencher) {
+    let mut gen = Pcg32::seed_from_u64(15);
+    let deep_expression_tree = generate_expression(BENCHMARK_LEN, &mut gen);
+
+    bencher.iter(|| {
+        build_operator_tree(&deep_expression_tree).unwrap()
+    });
+}
+
+#[bench]
+fn bench_parse_many_small_expressions(bencher: &mut Bencher) {
+    let mut gen = Pcg32::seed_from_u64(33);
+    let small_expressions = generate_small_expressions(BENCHMARK_LEN, &mut gen);
+
+    bencher.iter(|| {
+        for expression in &small_expressions {
+            black_box(build_operator_tree(&expression).unwrap());
+        }
+    });
+}