Variables globales (déclaration, affectation avec une expression et évaluation)

src/astprinter.rs

@@ -1,5 +1,5 @@
-use crate::expr::{Binary, Expr, ExprVisitor, Grouping, Literal, Unary};
-use crate::stmt::{ExpressionStatement, PrintStatement, StatementVisitor};
+use crate::expr::{Binary, Expr, ExprVisitor, Grouping, Literal, Unary, Variable};
+use crate::stmt::{ExpressionStatement, PrintStatement, StatementVisitor, VarStatement};
 
 pub struct ASTPrinter {
     pub(crate) depth: u32
@@ -58,8 +58,13 @@ impl ExprVisitor<()> for ASTPrinter {
             Expr::GroupingExpr(g) => { self.visit_grouping(g); }
             Expr::LiteralExpr(l) => { self.visit_literal(l); }
             Expr::UnaryExpr(u) => { self.visit_unary(u); }
+            Expr::VariableExpr(v) => { self.visit_variable(v); }
         }
     }
+
+    fn visit_variable(&mut self, v: &Variable) -> () {
+        println!("{}VARIABLE(name={})", self.ast_tab(), v.name.literal);
+    }
 }
 
 impl StatementVisitor<()> for ASTPrinter {
@@ -78,4 +83,18 @@ impl StatementVisitor<()> for ASTPrinter {
         self.depth-=1;
         print!(") ");
     }
+
+    fn visit_var_stmt(&mut self, v: &VarStatement) -> () {
+        println!("{} VAR_STMT(", self.ast_tab());
+        self.depth+=1;
+        println!("variable name = {}",&v.token.literal);
+        print!("variable initializer = ");
+        match &v.initializer {
+            Some(v) => { self.visit_expr(&v) }
+            None => {}
+        }
+
+        self.depth-=1;
+        print!(") ");
+    }
 }

src/environment.rs

@@ -0,0 +1,26 @@
+use std::collections::HashMap;
+use crate::expr::Literal;
+use crate::interpreter::RuntimeError;
+
+pub struct Environment {
+    pub values: HashMap<String, Literal>,
+}
+
+impl Environment {
+    pub fn new() -> Self {
+        Environment {
+            values : HashMap::new()
+        }
+    }
+
+    pub fn define(&mut self, name: String, value: Literal) {
+        self.values.insert(name, value);
+    }
+
+    pub fn get(&self, name: &String) -> Result<Literal, RuntimeError> {
+        match self.values.get(name) {
+            Some(s) => { Ok(s.clone()) } ,
+            None => { Err(RuntimeError { message: format!("Variable {} non définie", name) } ) }
+        }
+    }
+}

src/expr.rs

@@ -26,12 +26,18 @@ pub struct Unary {
     pub right: Box<Expr>,
 }
 
+#[derive(Clone)]
+pub struct Variable {
+    pub name: Token,
+}
+
 #[derive(Clone)]
 pub enum Expr {
     BinaryExpr(Binary),
     GroupingExpr(Grouping),
     LiteralExpr(Literal),
     UnaryExpr(Unary),
+    VariableExpr(Variable),
 }
 
 pub trait ExprVisitor<T> {
@@ -40,5 +46,6 @@ pub trait ExprVisitor<T> {
     fn visit_literal(&mut self, l: &Literal) ->T;
     fn visit_unary(&mut self, u: &Unary) -> T;
     fn visit_expr(&mut self, e: &Expr) -> T;
+    fn visit_variable(&mut self, v: &Variable) -> T;
 }
 

src/interpreter.rs

@@ -1,16 +1,28 @@
+use crate::environment::Environment;
 use crate::expr::Expr::UnaryExpr;
 use crate::expr::Expr::LiteralExpr;
 use crate::expr::Expr::GroupingExpr;
 use crate::expr::Expr::BinaryExpr;
+use crate::expr::Expr::VariableExpr;
 use crate::expr::Literal::LiteralString;
 use crate::expr::Literal::LiteralNumber;
 use crate::expr::Literal::LiteralBool;
 use crate::expr::Literal::LiteralNil;
-use crate::expr::{Binary, Expr, ExprVisitor, Grouping, Literal, Unary};
-use crate::stmt::{ExpressionStatement, PrintStatement, StatementVisitor};
+use crate::expr::{Binary, Expr, ExprVisitor, Grouping, Literal, Unary, Variable};
+use crate::stmt::{ExpressionStatement, PrintStatement, StatementVisitor, VarStatement};
 use crate::token_type::TokenType;
 
-pub struct Interpreter;
+pub struct Interpreter {
+    environment: Environment,
+}
+
+impl Interpreter {
+    pub fn new() -> Self {
+        Interpreter {
+            environment: Environment::new()
+        }
+    }
+}
 
 #[derive(Debug)]
 pub struct RuntimeError {
@@ -145,18 +157,23 @@ impl ExprVisitor<Result<Literal, RuntimeError>> for Interpreter {
             GroupingExpr(g) => { Ok(self.visit_grouping(&g)?) }
             LiteralExpr(l) => { Ok(self.visit_literal(&l)?) }
             UnaryExpr(u) => { Ok(self.visit_unary(&u)?) }
+            VariableExpr(v) => { Ok(self.visit_variable(&v)? )}
         }
     }
+
+    fn visit_variable(&mut self, v: &Variable) -> Result<Literal, RuntimeError> {
+        self.environment.get(&v.name.literal)
+    }
 }
 
 impl StatementVisitor<()> for Interpreter {
-    fn visit_expr_stmt(&mut self, e: &ExpressionStatement) -> () {
+    fn visit_expr_stmt(&mut self, e: &ExpressionStatement) {
         self.visit_expr(&e.expr).expect("Erreur pendant l'évaluation de l'expression.");
     }
 
-    fn visit_print(&mut self, p: &PrintStatement) -> () {
+    fn visit_print(&mut self, p: &PrintStatement) {
         match self.visit_expr(&p.expr) {
-            Ok(lit) => match (lit) {
+            Ok(lit) => match lit {
                 Literal::LiteralNumber(f) => { println!("{}", f); }
                 Literal::LiteralString(s) => { println!("{}", s); }
                 Literal::LiteralBool(b) => { println!("{}", b); }
@@ -165,6 +182,16 @@ impl StatementVisitor<()> for Interpreter {
             Err(e) => panic!("{}", e.message)
         }
     }
+
+    fn visit_var_stmt(&mut self, v: &VarStatement) {
+        match &v.initializer {
+            Some(e) => {
+                let value = self.visit_expr(&e).unwrap();
+                self.environment.define(v.token.literal.clone(), value);
+            }
+            None => {}
+        }
+    }
 }
 
 

src/main.rs

@@ -2,7 +2,6 @@ use std::{env, fs, io};
 use std::io::Write;
 use std::process;
 use crate::astprinter::ASTPrinter;
-use crate::expr::ExprVisitor;
 use crate::interpreter::Interpreter;
 use crate::parser::Parser;
 
@@ -14,15 +13,16 @@ mod expr;
 mod astprinter;
 mod parser;
 mod stmt;
+mod environment;
 
 use crate::scanner::Scanner;
 use crate::stmt::{Statement, StatementVisitor};
 
 // Exit codes from #include <sysexits.h>
 const EX_OK: i32 = 0;
-const EX_DATAERR: i32 = 65;
+//const EX_DATAERR: i32 = 65;
 const EX_USAGE : i32 = 66;
-const EX_EXECERR: i32 = 70;
+//const EX_EXECERR: i32 = 70;
 
 fn main() {
     let args: Vec<String> = env::args().collect();
@@ -81,15 +81,17 @@ fn run(src: String) -> i32 {
         match s {
             Statement::Expression(e) => { printer.visit_expr_stmt(&e) }
             Statement::Print(p) => { printer.visit_print(&p) }
+            Statement::Var(v) => { printer.visit_var_stmt(&v) }
         }
     }
 
     println!("Interpretation");
-    let mut interpreter = Interpreter;
+    let mut interpreter = Interpreter::new();
     for s in program {
         match s {
             Statement::Expression(e) => { interpreter.visit_expr_stmt(&e) }
             Statement::Print(p) => { interpreter.visit_print(&p) }
+            Statement::Var(v) => { interpreter.visit_var_stmt(&v) }
         }
     }
 

src/parser.rs

@@ -1,8 +1,8 @@
-use crate::expr::{Binary, Expr, Grouping, Unary};
+use crate::expr::{Binary, Expr, Grouping, Unary, Variable};
 use crate::expr::Literal::{LiteralBool, LiteralNumber, LiteralString};
 use crate::token::Token;
 use crate::token_type::TokenType;
-use crate::stmt::{ExpressionStatement, PrintStatement, Statement};
+use crate::stmt::{ExpressionStatement, PrintStatement, Statement, VarStatement};
 
 pub struct Parser {
     tokens: Vec<Token>,
@@ -60,15 +60,12 @@ impl Parser {
         return self.tokens[self.current - 1].clone();
     }
 
-    fn consume(&mut self, token_type: &TokenType, message: String) -> Result<(), ParseError> {
+    fn consume(&mut self, token_type: &TokenType, message: String) -> Result<Token, ParseError> {
         if self.check(token_type) {
-            self.advance();
-            return Ok(());
+            Ok(self.advance())
+        } else {
+            Err(ParseError { message })
         }
-
-        Err(ParseError {
-            message
-        })
     }
 
     fn synchronise(&mut self) {
@@ -192,6 +189,10 @@ impl Parser {
         if self.match_token(&[TokenType::String]) {
             return Ok(Expr::LiteralExpr(LiteralString(self.previous().literal)));
         }
+        if self.match_token(&[TokenType::Identifier]) {
+            return Ok(Expr::VariableExpr(Variable { name: self.previous() } ));
+        }
+
         if self.match_token(&[TokenType::LeftParen]) {
             let expr = self.expression()?;
             self.consume(&TokenType::RightParen, String::from("Expect ')' after expression."))?;
@@ -205,7 +206,7 @@ impl Parser {
         }
     }
 
-    fn statement(&mut self) -> Statement {
+    fn statement(&mut self) -> Result<Statement, ParseError> {
         if self.match_token(&[TokenType::Print]) {
             self.print_statement()
         } else {
@@ -213,22 +214,53 @@ impl Parser {
         }
     }
 
-    fn print_statement(&mut self) -> Statement {
-        let e = self.expression().unwrap();
-        self.consume(&TokenType::Semicolon, String::from("; attendu")).unwrap();
-        Statement::Print(PrintStatement{ expr: e })
+    fn print_statement(&mut self) -> Result<Statement, ParseError> {
+        match self.expression() {
+            Ok(e) => {
+                self.consume(&TokenType::Semicolon, String::from("; attendu"))?;
+                Ok(Statement::Print(PrintStatement{ expr: e }))
+            }
+            Err(e ) => { Err(e) }
+        }
     }
 
-    fn expr_statement(&mut self) -> Statement {
-        let e = self.expression().unwrap();
-        self.consume(&TokenType::Semicolon, String::from("; attendu")).unwrap();
-        Statement::Expression(ExpressionStatement{ expr: e })
+    fn expr_statement(&mut self) -> Result<Statement, ParseError> {
+        match self.expression() {
+            Ok(e) => {
+                self.consume(&TokenType::Semicolon, String::from("; attendu"))?;
+                Ok(Statement::Expression(ExpressionStatement{ expr: e }))
+            }
+            Err(e ) => { Err(e) }
+        }
+    }
+
+    fn declaration(&mut self) -> Result<Statement, ParseError> {
+        if self.match_token(&[TokenType::Var]) {
+            self.var_declaration()
+        } else {
+            self.statement()
+        }
+    }
+
+    fn var_declaration(&mut self) -> Result<Statement, ParseError> {
+        let name = self.consume(&TokenType::Identifier, String::from("nom de variable attendu"))?;
+
+        let mut initializer: Option<Expr> = None;
+        if self.match_token(&[TokenType::Equal]) {
+            initializer = Some(self.expression()?);
+        }
+
+        self.consume(&TokenType::Semicolon, String::from("; attendu"))?;
+        Ok(Statement::Var(VarStatement{ token: name, initializer }))
     }
 
     pub fn parse(&mut self) -> Vec<Statement> {
         let mut statements= Vec::new();
         while !self.is_at_end() {
-            statements.push(self.statement());
+            match self.declaration() {
+                Ok(stmt) => statements.push(stmt),
+                Err(_e) => self.synchronise(),
+            }
         }
 
         statements

src/stmt.rs

@@ -1,9 +1,11 @@
 use crate::expr::Expr;
+use crate::token::Token;
 
 #[derive(Clone)]
 pub enum Statement {
     Expression(ExpressionStatement),
-    Print(PrintStatement)
+    Print(PrintStatement),
+    Var(VarStatement),
 }
 
 #[derive(Clone)]
@@ -16,7 +18,14 @@ pub struct PrintStatement {
     pub expr: Expr
 }
 
+#[derive(Clone)]
+pub struct VarStatement {
+    pub token: Token,
+    pub initializer: Option<Expr>
+}
+
 pub trait StatementVisitor<T> {
     fn visit_expr_stmt(&mut self, e: &ExpressionStatement) -> T;
     fn visit_print(&mut self, p: &PrintStatement) -> T;
+    fn visit_var_stmt(&mut self, v: &VarStatement) -> T;
 }