docs(tfhe): format regex_engine and add make recipes to run it

Makefile

@@ -21,6 +21,10 @@ else
 		AVX512_FEATURE=
 endif
 
+# Variables used only for regex_engine example
+REGEX_STRING?=''
+REGEX_PATTERN?=''
+
 .PHONY: rs_check_toolchain # Echo the rust toolchain used for checks
 rs_check_toolchain:
 	@echo $(RS_CHECK_TOOLCHAIN)
@@ -242,6 +246,12 @@ test_user_doc: install_rs_build_toolchain
 		--features=$(TARGET_ARCH_FEATURE),boolean,shortint,integer,internal-keycache -p tfhe \
 		-- test_user_docs::
 
+.PHONY: test_regex_engine # Run tests for regex_engine example
+test_regex_engine: install_rs_build_toolchain
+	RUSTFLAGS="$(RUSTFLAGS)" cargo $(CARGO_RS_BUILD_TOOLCHAIN) test --profile $(CARGO_PROFILE) \
+		--example regex_engine \
+		--features=$(TARGET_ARCH_FEATURE),integer
+
 .PHONY: doc # Build rust doc
 doc: install_rs_check_toolchain
 	RUSTDOCFLAGS="--html-in-header katex-header.html -Dwarnings" \
@@ -326,6 +336,13 @@ measure_boolean_key_sizes: install_rs_check_toolchain
 	--example boolean_key_sizes \
 	--features=$(TARGET_ARCH_FEATURE),boolean,internal-keycache
 
+.PHONY: regex_engine # Run regex_engine example
+regex_engine: install_rs_check_toolchain
+	RUSTFLAGS="$(RUSTFLAGS)" cargo $(CARGO_RS_CHECK_TOOLCHAIN) run --profile $(CARGO_PROFILE) \
+	--example regex_engine \
+	--features=$(TARGET_ARCH_FEATURE),integer \
+	-- $(REGEX_STRING) $(REGEX_PATTERN)
+
 .PHONY: pcc # pcc stands for pre commit checks
 pcc: no_tfhe_typo check_fmt doc clippy_all check_compile_tests
 

tfhe/docs/regex/tutorial.md

@@ -446,7 +446,7 @@ reusing those where possible.
 # Trying out the example implementation
 
 The implementation that guided the writing of this tutorial can be found
-under `thfe/examples/regex_engine`.
+under `tfhe/examples/regex_engine`.
 
 When compiling with `--example regex_engine`, a binary is produced that serves
 as a basic demo. Simply call it with first argument the content string and

tfhe/examples/regex_engine/ciphertext.rs

@@ -1,7 +1,6 @@
+use anyhow::{anyhow, Result};
+use tfhe::integer::{gen_keys_radix, RadixCiphertextBig, RadixClientKey, ServerKey};
 use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2;
-use tfhe::integer::gen_keys_radix;
-use tfhe::integer::{RadixCiphertextBig, RadixClientKey, ServerKey};
-use anyhow::{Result, anyhow};
 
 pub type StringCiphertext = Vec<RadixCiphertextBig>;
 
@@ -17,5 +16,5 @@ pub fn encrypt_str(client_key: &RadixClientKey, s: &str) -> Result<StringCiphert
 
 pub fn gen_keys() -> (RadixClientKey, ServerKey) {
     let num_block = 4;
-    gen_keys_radix(&PARAM_MESSAGE_2_CARRY_2, num_block)
+    gen_keys_radix(PARAM_MESSAGE_2_CARRY_2, num_block)
 }

tfhe/examples/regex_engine/engine.rs

@@ -1,8 +1,8 @@
+use crate::execution::{Executed, Execution, LazyExecution};
+use crate::parser::{parse, RegExpr};
 use anyhow::Result;
 use std::rc::Rc;
 use tfhe::integer::{RadixCiphertextBig, ServerKey};
-use crate::parser::{parse, RegExpr};
-use crate::execution::{Executed, Execution, LazyExecution};
 
 pub fn has_match(
     sk: &ServerKey,
@@ -25,7 +25,7 @@ pub fn has_match(
             .0
     } else {
         branches[1..]
-            .into_iter()
+            .iter()
             .fold(branches[0](&mut exec), |res, branch| {
                 let branch_res = branch(&mut exec);
                 exec.ct_or(res, branch_res)
@@ -47,14 +47,14 @@ fn build_branches(
 ) -> Vec<(LazyExecution, usize)> {
     trace!("program pointer: regex={:?}, content pos={}", re, c_pos);
     match re {
-        RegExpr::SOF => {
+        RegExpr::Sof => {
             if c_pos == 0 {
                 return vec![(Rc::new(|exec| exec.ct_true()), c_pos)];
             } else {
                 return vec![];
             }
         }
-        RegExpr::EOF => {
+        RegExpr::Eof => {
             if c_pos == content.len() {
                 return vec![(Rc::new(|exec| exec.ct_true()), c_pos)];
             } else {
@@ -216,11 +216,9 @@ mod tests {
     use crate::engine::has_match;
     use test_case::test_case;
 
-    use tfhe::integer::{ServerKey, RadixClientKey};
     use crate::ciphertext::{encrypt_str, gen_keys, StringCiphertext};
-    use bincode;
     use lazy_static::lazy_static;
-    use std::io::Write;
+    use tfhe::integer::{RadixClientKey, ServerKey};
 
     lazy_static! {
         pub static ref KEYS: (RadixClientKey, ServerKey) = gen_keys();

tfhe/examples/regex_engine/execution.rs

@@ -185,10 +185,7 @@ impl Execution {
 
                 let mut ct_a = a.0.clone();
                 let mut ct_b = exec.ct_constant(1).0;
-                (
-                    exec.sk.smart_bitxor(&mut ct_a, &mut ct_b),
-                    ctx.clone(),
-                )
+                (exec.sk.smart_bitxor(&mut ct_a, &mut ct_b), ctx.clone())
             }),
         )
     }

tfhe/examples/regex_engine/main.rs

@@ -1,13 +1,13 @@
 #[macro_use]
 extern crate log;
 
-mod engine;
 mod ciphertext;
+mod engine;
 mod execution;
 mod parser;
 
-use std::env;
 use env_logger::Env;
+use std::env;
 
 fn main() {
     let env = Env::default().filter_or("RUST_LOG", "info");