AstBuilder: generate basic global constants

src/ast_builder.rs

@@ -1,29 +1,107 @@
+use rand::Rng;
+use rand_distr::Distribution;
+
 use crate::params::Params;
 use crate::ast::{
+    Expr,
+    Statement,
     Quantifier,
     BaseType,
     GlobalBlock,
     Block,
     Literal,
     Declaration,
+    DeclarationBuilder,
     Variable,
+    VariableBuilder,
     BinaryOperator,
 };
 
 pub struct AstBuilder {
     params: Params,
     ast: GlobalBlock,
+    name_counter: u64,
+    rng: rand::rngs::ThreadRng,
 }
 
 impl AstBuilder {
     pub fn from(params: Params) -> Self {
         Self {
             params,
+            rng: rand::thread_rng(),
+            name_counter: 0,
             ast: GlobalBlock::default(),
         }
     }
 
-    pub fn generate(&self) {
+    pub fn generate(&mut self) {
+
+        let mut p: f64;
+
+        loop {
+            p = self.rng.gen();
+
+            if p < self.params.global_flow.end_generation {
+                break;
+            } else {
+                let decl = self.gen_decl();
+                self.ast.push(decl);
+            }
+        }
+    }
+
+    fn gen_decl(&mut self) -> Box<dyn Statement> {
+        let t = BaseType::Int;
+        let v = self.gen_variable_quantified(t, Quantifier::Const);
+
+        Box::new(
+            DeclarationBuilder::default()
+                .variable(v)
+                .assn(self.gen_literal(t))
+                .build()
+                .unwrap()
+        )
+    }
+
+    fn gen_variable(&mut self, t: BaseType) -> Variable {
+        VariableBuilder::default()
+            .type_(t)
+            .name(self.gen_name())
+            .quantifer(Quantifier::Var)
+            .build()
+            .unwrap()
+    }
+
+    fn gen_variable_quantified(&mut self, t: BaseType, q: Quantifier) -> Variable {
+        VariableBuilder::default()
+            .type_(t)
+            .name(self.gen_name())
+            .quantifer(q)
+            .build()
+            .unwrap()
+    }
+
+
+    fn gen_name(&mut self) -> String {
+        let s = format!("_{}", self.name_counter);
+        self.name_counter += 1;
+        s
+    }
+
+    //fn gen_expr(&mut self, type_: BaseType) -> Box<dyn Expr> {
+    //}
+
+    fn gen_literal(&mut self, t: BaseType) -> Literal {
+        match t {
+            BaseType::Int => {
+                let r = rand_distr::Beta::new(0.5, 0.5).unwrap();
+                let i: i32 = (r.sample(&mut self.rng) * (i32::MAX as f64)) as i32;
+                Literal::Int(i)
+            }
+            BaseType::Real => Literal::Real(1.0),
+            BaseType::Never => panic!("Attempted to generate literal of type Never"),
+            BaseType::Unset => panic!("Attempted to generate literal of type Unset"),
+        }
     }
 }