Implemented flatzinc

Author: radevgit

.gitignore

@@ -24,3 +24,4 @@ target
 # Added by cargo
 
 /target
+/zinc

Cargo.lock

@@ -17,8 +17,7 @@ readme = "README.md"
 crate-type = ["lib"]
 
 [dependencies]
-# Use local path during development
-selen = { version = "0.9", path = "../selen" }
+selen = "0.9"
 
 [dev-dependencies]
 

Cargo.toml

@@ -27,7 +27,42 @@ zelen = "0.1"
 
 ## Quick Start
 
-### From FlatZinc String
+### Recommended API: FlatZincSolver
+
+The easiest way to use Zelen is with the `FlatZincSolver` - it provides automatic FlatZinc-compliant output:
+
+```rust
+use zelen::prelude::*;
+
+let fzn = r#"
+    var 1..10: x;
+    var 1..10: y;
+    constraint int_eq(x, 5);
+    constraint int_plus(x, y, 12);
+    solve satisfy;
+"#;
+
+let mut solver = FlatZincSolver::new();
+solver.load_str(fzn)?;
+solver.solve()?;
+
+// Automatic FlatZinc-compliant output with statistics
+print!("{}", solver.to_flatzinc());
+// Outputs:
+// x = 5;
+// y = 7;
+// ----------
+// ==========
+// %%%mzn-stat: solutions=1
+// %%%mzn-stat: nodes=0
+// %%%mzn-stat: propagations=0
+// %%%mzn-stat: solveTime=0.001
+// %%%mzn-stat-end
+```
+
+### Low-Level API: Direct Model Integration
+
+For more control, use the Model integration API:
 
 ```rust
 use zelen::prelude::*;
@@ -103,54 +138,59 @@ if let Ok(solution) = model.solve() {
 }
 ```
 
-### FlatZinc-Compliant Output
+### Configurable Output and Statistics
 
-Zelen provides a formatter to output solutions according to the FlatZinc specification:
+Control statistics and solution enumeration:
 
 ```rust
 use zelen::prelude::*;
-use zelen::output::format_solution;
-use std::collections::HashMap;
 
-let fzn = r#"
-    var 1..10: x;
-    var 1..10: y;
-    constraint int_eq(x, 5);
-    constraint int_eq(y, 3);
-    solve satisfy;
-"#;
+let fzn = "var 1..10: x; solve satisfy;";
 
-let mut model = Model::default();
-model.from_flatzinc_str(fzn)?;
+// Configure solver options
+let mut solver = FlatZincSolver::new();
+solver.with_statistics(true);       // Enable/disable statistics
+solver.max_solutions(3);            // Find up to 3 solutions
+solver.find_all_solutions();        // Find all solutions
 
-match model.solve() {
-    Ok(solution) => {
-        // Get variable names from the parser (you'd track these during parsing)
-        let var_names = HashMap::from([
-            (x_var_id, "x".to_string()),
-            (y_var_id, "y".to_string()),
-        ]);
-        
-        // Format according to FlatZinc spec
-        let output = format_solution(&solution, &var_names);
-        print!("{}", output);
-        // Outputs:
-        // x = 5;
-        // y = 3;
-        // ----------
-    }
-    Err(_) => {
-        println!("{}", zelen::output::format_no_solution());
-        // Outputs: =====UNSATISFIABLE=====
-    }
-}
+solver.load_str(fzn)?;
+solver.solve()?;
+
+// Get formatted output
+let output = solver.to_flatzinc();  // Returns String
+solver.print_flatzinc();            // Prints directly
+
+// Access solutions programmatically
+let count = solver.solution_count();
+let solution = solver.get_solution(0);
+```
+
+### FlatZinc Specification Compliance
+
+Zelen follows the [FlatZinc specification](https://docs.minizinc.dev/en/stable/fzn-spec.html#output) exactly:
+
+**Output Format:**
+- Variable assignments: `varname = value;`
+- Solution separator: `----------`
+- Search complete: `==========`
+- Unsatisfiable: `=====UNSATISFIABLE=====`
+
+**Statistics Format** (optional, configurable):
+```
+%%%mzn-stat: solutions=1
+%%%mzn-stat: nodes=10
+%%%mzn-stat: failures=0
+%%%mzn-stat: propagations=21
+%%%mzn-stat: variables=4
+%%%mzn-stat: propagators=1
+%%%mzn-stat: solveTime=0.001
+%%%mzn-stat: peakMem=1.00
+%%%mzn-stat-end
 ```
 
-The output format follows the [FlatZinc specification](https://docs.minizinc.dev/en/stable/fzn-spec.html#output):
-- Each variable assignment on its own line: `varname = value;`
-- Separator line `----------` marks the end of a solution
-- `=====UNSATISFIABLE=====` when no solution exists
-- `=====UNKNOWN=====` when satisfiability cannot be determined
+All statistics are automatically extracted from Selen's solver:
+- **Standard** (FlatZinc spec): solutions, nodes, failures, solveTime (seconds), peakMem (MB)
+- **Extended**: propagations, variables, propagators
 
 ## Using with MiniZinc
 
@@ -219,17 +259,32 @@ Zelen has been tested on 851 real-world FlatZinc files from the OR-Tools test su
 
 ## Examples
 
-Check the `examples/` directory for more complete examples:
+The repository includes comprehensive examples demonstrating different aspects of the library:
 
-```bash
-# Basic FlatZinc parsing and solving
-cargo run --example flatzinc_simple
+### Basic Usage
+- **`simple_usage.rs`** - Basic constraint solving with FlatZincContext API
+- **`clean_api.rs`** - High-level FlatZincSolver API with automatic output formatting
+- **`solver_demo.rs`** - Demonstrates solving various constraint problem types
+
+### FlatZinc Integration
+- **`flatzinc_simple.rs`** - Simple FlatZinc model solving
+- **`flatzinc_output.rs`** - FlatZinc-compliant output formatting
 
-# FlatZinc-compliant output formatting
-cargo run --example flatzinc_output
+### Multiple Solutions & Configuration
+- **`multiple_solutions.rs`** - Enumerate multiple solutions with configurable limits
+- **`spec_compliance.rs`** - FlatZinc specification compliance demonstration
+- **`optimization_test.rs`** - Minimize/maximize with optimal and intermediate solutions
 
-# Complete solver demo with multiple problem types
-cargo run --example solver_demo
+### Statistics & Monitoring
+- **`enhanced_statistics.rs`** - All available solver statistics from Selen
+- **`statistics_units.rs`** - Statistics unit verification (seconds, megabytes)
+
+Run any example with:
+```bash
+cargo run --example <name>
+# For instance:
+cargo run --example clean_api
+cargo run --example multiple_solutions
 ```
 
 ## Testing

README.md

@@ -14,7 +14,7 @@ This document provides a high-level overview of the FlatZinc integration with Se
 
 MiniZinc can export constraint satisfaction problems to FlatZinc format (*.fzn):
 - **Flattening Process**: https://docs.minizinc.dev/en/stable/flattening.html
-- **FlatZinc Specification**: https://docs.minizinc.dev/en/latest/fzn-spec.html
+- **FlatZinc Specification**: https://docs.minizinc.dev/en/stable/fzn-spec.html
   - BNF grammar is at the end of the spec document
 - **Latest MiniZinc Release**: 2.9.4
 
@@ -181,7 +181,7 @@ A: Tokenizer + recursive-descent for statements. Expression parser TBD. See [ZIN
 
 ## References
 
-- [FlatZinc 2.8.4 Specification](https://docs.minizinc.dev/en/latest/fzn-spec.html)
+- [FlatZinc Specification](https://docs.minizinc.dev/en/stable/fzn-spec.html)
 - [MiniZinc Documentation](https://docs.minizinc.dev/)
 - [MiniZinc Global Constraints](https://docs.minizinc.dev/en/stable/lib-globals.html)
 

docs/FLATZINC.md

@@ -1,5 +1,7 @@
-https://docs.minizinc.dev/en/stable/flattening.html
-https://docs.minizinc.dev/en/stable/fzn-spec.html
+# FlatZinc Documentation
+
+- Flattening: https://docs.minizinc.dev/en/stable/flattening.html
+- FlatZinc Specification: https://docs.minizinc.dev/en/stable/fzn-spec.html
 
 
 
@@ -121,11 +123,11 @@ pub fn import_flatzinc_str(input: &str) -> Result<Model, ZincImportError>;
 
 ## 2. MiniZinc and FlatZinc Standards and References
 
-- **MiniZinc Language Reference (2.8.4):**  
-	- [MiniZinc 2.8.4 Language Reference](https://www.minizinc.org/doc-2.8.4/en/index.html)
+- **MiniZinc Language Reference:**  
+	- [MiniZinc Language Reference](https://docs.minizinc.dev/en/stable/)
 	- [MiniZinc Grammar (BNF)](https://github.com/MiniZinc/libminizinc/blob/master/doc/grammar/minizinc.bnf)
-- **FlatZinc Specification (2.8.4):**  
-	- [FlatZinc 2.8.4 Specification](https://www.minizinc.org/doc-2.8.4/en/fzn-spec.html)
+- **FlatZinc Specification:**  
+	- [FlatZinc Specification](https://docs.minizinc.dev/en/stable/fzn-spec.html)
 - **File Types:**  
 	- `.mzn` — Model files (constraints, variables, parameters)
 	- `.dzn` — Data files (parameter assignments)
@@ -199,11 +201,11 @@ pub fn import_flatzinc_str(input: &str) -> Result<Model, ZincImportError>;
 
 ## 5. References and Resources
 
-- [MiniZinc 2.8.4 Language Reference](https://www.minizinc.org/doc-2.8.4/en/index.html)
+- [MiniZinc Language Reference](https://docs.minizinc.dev/en/stable/)
 - [MiniZinc BNF Grammar](https://github.com/MiniZinc/libminizinc/blob/master/doc/grammar/minizinc.bnf)
-- [FlatZinc 2.8.4 Specification](https://www.minizinc.org/doc-2.8.4/en/fzn-spec.html)
-- [MiniZinc Example Models](https://www.minizinc.org/examples.html)
-- [MiniZinc Standard Library](https://www.minizinc.org/doc-2.8.4/en/lib-globals.html)
+- [FlatZinc Specification](https://docs.minizinc.dev/en/stable/fzn-spec.html)
+- [MiniZinc Example Models](https://www.minizinc.org/software/)
+- [MiniZinc Standard Library](https://docs.minizinc.dev/en/stable/lib-globals.html)
 
 ---
 

docs/ZINC.md

@@ -0,0 +1,76 @@
+//! Clean API example - the way it should be!
+//!
+//! Just call the methods: load → solve → to_flatzinc()
+
+use zelen::prelude::*;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    println!("=== FlatZinc Solver - Clean API ===\n");
+
+    // Example 1: Simple usage
+    println!("Example 1: Simple Problem");
+    println!("-------------------------");
+    {
+        let fzn = r#"
+            var 1..10: x;
+            var 1..10: y;
+            constraint int_eq(x, 5);
+            constraint int_plus(x, y, 12);
+            solve satisfy;
+        "#;
+
+        let mut solver = FlatZincSolver::new();
+        solver.load_str(fzn)?;
+        solver.solve().ok();
+        
+        print!("{}", solver.to_flatzinc());
+    }
+
+    // Example 2: Unsatisfiable problem
+    println!("\nExample 2: Unsatisfiable");
+    println!("------------------------");
+    {
+        let fzn = r#"
+            var 1..5: x;
+            constraint int_eq(x, 3);
+            constraint int_eq(x, 7);
+            solve satisfy;
+        "#;
+
+        let mut solver = FlatZincSolver::new();
+        solver.load_str(fzn)?;
+        solver.solve().ok();
+        
+        print!("{}", solver.to_flatzinc());
+    }
+
+    // Example 3: From file
+    println!("\nExample 3: N-Queens");
+    println!("-------------------");
+    {
+        let fzn = r#"
+            array[1..4] of var 1..4: q;
+            constraint all_different(q);
+            solve satisfy;
+        "#;
+
+        let mut solver = FlatZincSolver::new();
+        solver.load_str(fzn)?;
+        
+        if solver.solve().is_ok() {
+            solver.print_flatzinc();
+        } else {
+            println!("No solution found");
+        }
+    }
+
+    println!("\n=== API Summary ===");
+    println!("1. FlatZincSolver::new()         - create solver");
+    println!("2. solver.load_str(fzn)          - load FlatZinc");
+    println!("3. solver.solve()                - solve (satisfy/minimize/maximize)");
+    println!("4. solver.to_flatzinc()          - get formatted output with statistics");
+    println!("5. solver.print_flatzinc()       - print directly");
+    println!("\nNo manual formatting, no manual context, no manual anything!");
+
+    Ok(())
+}