111 lines
3.3 KiB
Rust
111 lines
3.3 KiB
Rust
use schala_lang::parsing::{AST, Statement, Declaration, Expression, ExpressionType, Operation};
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pub struct ReplState {
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}
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type EvalResult<T> = Result<T, String>;
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enum FullyEvaluatedExpr {
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UnsignedInt(u64),
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SignedInt(i64),
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Float(f64),
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Str(String),
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Bool(bool),
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}
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impl ReplState {
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pub fn new() -> ReplState {
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ReplState { }
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}
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pub fn evaluate(&mut self, ast: AST) -> Vec<String> {
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let mut acc = vec![];
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for statement in ast.0 {
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match self.eval_statement(statement) {
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Ok(output) => {
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if let Some(s) = output {
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acc.push(s);
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}
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},
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Err(error) => {
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acc.push(format!("Error: {}", error));
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return acc;
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},
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}
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}
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acc
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}
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}
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impl ReplState {
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fn eval_statement(&mut self, statement: Statement) -> EvalResult<Option<String>> {
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use self::FullyEvaluatedExpr::*;
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match statement {
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Statement::ExpressionStatement(expr) => {
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self.eval_expr(expr).map( |eval| {
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match eval {
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UnsignedInt(n) => Some(format!("{}", n)),
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SignedInt(n) => Some(format!("{}", n)),
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Float(f) => Some(format!("{}", f)),
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Str(s) => Some(format!("\"{}\"", s)),
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Bool(b) => Some(format!("{}", b)),
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}
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})
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},
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Statement::Declaration(decl) => {
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self.eval_decl(decl).map(|_| None)
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}
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}
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}
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fn eval_decl(&mut self, _decl: Declaration) -> EvalResult<()> {
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Err("Not implmemented".to_string())
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}
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fn eval_expr(&mut self, expr: Expression) -> EvalResult<FullyEvaluatedExpr> {
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use self::ExpressionType::*;
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use self::FullyEvaluatedExpr::*;
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let expr_type = expr.0;
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match expr_type {
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IntLiteral(n) => Ok(UnsignedInt(n)),
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FloatLiteral(f) => Ok(Float(f)),
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StringLiteral(s) => Ok(Str(s.to_string())),
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BoolLiteral(b) => Ok(Bool(b)),
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PrefixExp(op, expr) => self.eval_prefix_exp(op, expr),
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BinExp(op, lhs, rhs) => self.eval_binexp(op, lhs, rhs),
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_ => Err(format!("Unimplemented")),
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}
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}
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fn eval_binexp(&mut self, op: Operation, lhs: Box<Expression>, rhs: Box<Expression>) -> EvalResult<FullyEvaluatedExpr> {
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use self::FullyEvaluatedExpr::*;
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let evaled_lhs = self.eval_expr(*lhs)?;
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let evaled_rhs = self.eval_expr(*rhs)?;
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let opstr: &str = &op.0;
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Ok(match (opstr, evaled_lhs, evaled_rhs) {
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("+", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l + r),
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("++", Str(s1), Str(s2)) => Str(format!("{}{}", s1, s2)),
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("-", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l - r),
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("*", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l * r),
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("/", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l / r),
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("%", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l % r),
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_ => return Err(format!("Runtime error: not yet implemented")),
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})
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}
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fn eval_prefix_exp(&mut self, op: Operation, expr: Box<Expression>) -> EvalResult<FullyEvaluatedExpr> {
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use self::FullyEvaluatedExpr::*;
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let evaled_expr = self.eval_expr(*expr)?;
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let opstr: &str = &op.0;
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Ok(match (opstr, evaled_expr) {
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("!", Bool(true)) => Bool(false),
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("!", Bool(false)) => Bool(true),
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("-", UnsignedInt(n)) => SignedInt(-1*(n as i64)),
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("-", SignedInt(n)) => SignedInt(-1*(n as i64)),
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_ => return Err(format!("Runtime error: not yet implemented")),
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})
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}
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}
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