Make log encoding domain threshold configurable by adding log_encoding_domain_threshold config option

cspuz_core/src/config.rs

@@ -13,6 +13,7 @@ pub struct Config {
     pub force_use_log_encoding: bool,
     pub use_native_extension_supports: bool,
     pub direct_encoding_for_binary_vars: bool,
+    pub encoding_domain_threshold: usize,
     pub merge_equivalent_variables: bool,
     pub alldifferent_bijection_constraints: bool,
     pub glucose_random_seed: Option<f64>,
@@ -53,6 +54,7 @@ impl Config {
             force_use_log_encoding: false,
             use_native_extension_supports: false,
             direct_encoding_for_binary_vars: false,
+            encoding_domain_threshold: 500,
             merge_equivalent_variables: false,
             alldifferent_bijection_constraints: false,
             glucose_random_seed: None,
@@ -156,6 +158,7 @@ impl Config {
         opts.optopt("", "domain-product-threshold", "Specify the threshold of domain product for introducing an auxiliary variable by Tseitin transformation.", "THRESHOLD");
         opts.optopt("", "native-linear-encoding-terms", "Specify the maximum number of terms in a linear sum which is encoded by the native linear constraint (0 for disabling this).", "TERMS");
         opts.optopt("", "native-linear-encoding-domain-product", "Specify the minimum domain product of linear sums which are encoded by the native linear constraint.", "DOMAIN_PRODUCT");
+        opts.optopt("", "encoding-domain-threshold", "Specify the domain size threshold for choosing encoding schemes (direct vs order vs log).", "THRESHOLD");
 
         opts.optopt("", "backend", "Specify the SAT backend", "BACKEND");
         opts.optopt(
@@ -236,6 +239,19 @@ impl Config {
             };
             config.native_linear_encoding_domain_product_threshold = v;
         }
+        if let Some(s) = matches.opt_str("encoding-domain-threshold") {
+            let v = match s.parse::<usize>() {
+                Ok(v) => v,
+                Err(f) => {
+                    println!(
+                        "error: parse failed for --encoding-domain-threshold: {}",
+                        f,
+                    );
+                    std::process::exit(1);
+                }
+            };
+            config.encoding_domain_threshold = v;
+        }
         if let Some(s) = matches.opt_str("backend") {
             if s == "glucose" {
                 config.backend = Backend::Glucose;

cspuz_core/src/encoder/mod.rs

@@ -597,8 +597,7 @@ fn decide_encode_schemes(
         for &var in new_vars {
             let repr = norm_vars.int_var(var);
             if let IntVarRepresentation::Domain(domain) = repr {
-                if domain.num_candidates() > 500 && complex_constraints_vars.contains(&var) {
-                    // TODO: make this configurable
+                if domain.num_candidates() > config.encoding_domain_threshold && complex_constraints_vars.contains(&var) {
                     scheme.insert(var, EncodeScheme::Log);
                 }
             }
@@ -688,7 +687,7 @@ fn decide_encode_schemes(
         for &var in &direct_encoding_vars {
             let repr = norm_vars.int_var(var);
             let use_direct_encoding = match repr {
-                IntVarRepresentation::Domain(domain) => domain.num_candidates() <= 500,
+                IntVarRepresentation::Domain(domain) => domain.num_candidates() <= config.encoding_domain_threshold,
                 _ => true,
             };
             if use_direct_encoding {
@@ -1564,4 +1563,17 @@ mod tests {
             }
         }
     }
+
+    #[test]
+    fn test_encoding_domain_threshold_configurable() {
+        let mut config = Config::default();
+        assert_eq!(config.encoding_domain_threshold, 500); // default value
+
+        config.encoding_domain_threshold = 1000;
+        assert_eq!(config.encoding_domain_threshold, 1000); // changed value
+
+        // Test that the field exists and can be modified
+        config.encoding_domain_threshold = 100;
+        assert_eq!(config.encoding_domain_threshold, 100);
+    }
 }