forked from extern/nushell
125 lines
3.5 KiB
Rust
125 lines
3.5 KiB
Rust
use std::collections::HashMap;
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use crate::{parser::Operator, Block, Call, Expr, Expression, ParserState, Span, Statement, VarId};
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#[derive(Debug)]
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pub enum ShellError {
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Mismatch(String, Span),
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Unsupported(Span),
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InternalError(String),
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}
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#[derive(Debug, Clone)]
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pub enum Value {
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Int { val: i64, span: Span },
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Unknown,
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}
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impl Value {
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pub fn add(&self, rhs: &Value) -> Result<Value, ShellError> {
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match (self, rhs) {
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(Value::Int { val: lhs, .. }, Value::Int { val: rhs, .. }) => Ok(Value::Int {
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val: lhs + rhs,
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span: Span::unknown(),
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}),
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_ => Ok(Value::Unknown),
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}
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}
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}
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pub struct State<'a> {
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pub parser_state: &'a ParserState,
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}
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pub struct Stack {
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pub vars: HashMap<VarId, Value>,
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}
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impl Stack {
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pub fn get_var(&self, var_id: VarId) -> Result<Value, ShellError> {
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match self.vars.get(&var_id) {
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Some(v) => Ok(v.clone()),
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_ => Err(ShellError::InternalError("variable not found".into())),
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}
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}
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}
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pub fn eval_operator(
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state: &State,
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stack: &mut Stack,
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op: &Expression,
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) -> Result<Operator, ShellError> {
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match op {
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Expression {
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expr: Expr::Operator(operator),
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..
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} => Ok(operator.clone()),
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Expression { span, .. } => Err(ShellError::Mismatch("operator".to_string(), *span)),
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}
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}
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fn eval_call(state: &State, stack: &mut Stack, call: &Call) -> Result<Value, ShellError> {
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let decl = state.parser_state.get_decl(call.decl_id);
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if let Some(block_id) = decl.body {
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let block = state.parser_state.get_block(block_id);
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eval_block(state, stack, block)
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} else {
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Ok(Value::Unknown)
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}
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}
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pub fn eval_expression(
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state: &State,
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stack: &mut Stack,
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expr: &Expression,
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) -> Result<Value, ShellError> {
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match &expr.expr {
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Expr::Int(i) => Ok(Value::Int {
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val: *i,
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span: expr.span,
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}),
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Expr::Var(var_id) => stack.get_var(*var_id),
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Expr::Call(call) => eval_call(state, stack, call),
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Expr::ExternalCall(_, _) => Err(ShellError::Unsupported(expr.span)),
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Expr::Operator(_) => Ok(Value::Unknown),
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Expr::BinaryOp(lhs, op, rhs) => {
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let lhs = eval_expression(state, stack, &lhs)?;
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let op = eval_operator(state, stack, &op)?;
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let rhs = eval_expression(state, stack, &rhs)?;
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match op {
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Operator::Plus => lhs.add(&rhs),
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_ => Ok(Value::Unknown),
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}
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}
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Expr::Subexpression(block_id) => {
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let block = state.parser_state.get_block(*block_id);
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eval_block(state, stack, block)
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}
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Expr::Block(_) => Err(ShellError::Unsupported(expr.span)),
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Expr::List(_) => Err(ShellError::Unsupported(expr.span)),
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Expr::Table(_, _) => Err(ShellError::Unsupported(expr.span)),
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Expr::Literal(_) => Err(ShellError::Unsupported(expr.span)),
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Expr::String(_) => Err(ShellError::Unsupported(expr.span)),
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Expr::Signature(_) => Err(ShellError::Unsupported(expr.span)),
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Expr::Garbage => Err(ShellError::Unsupported(expr.span)),
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}
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}
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pub fn eval_block(state: &State, stack: &mut Stack, block: &Block) -> Result<Value, ShellError> {
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let mut last = Ok(Value::Unknown);
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for stmt in &block.stmts {
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match stmt {
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Statement::Expression(expression) => {
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last = Ok(eval_expression(state, stack, expression)?);
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}
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_ => {}
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}
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}
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last
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}
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