2019-05-28 08:45:18 +02:00
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use crate::parser::ast;
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use crate::prelude::*;
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use derive_new::new;
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#[derive(new)]
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crate struct Scope {
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it: Value,
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}
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impl Scope {
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crate fn empty() -> Scope {
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Scope {
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it: Value::nothing(),
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}
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}
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}
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crate fn evaluate_expr(expr: &ast::Expression, scope: &Scope) -> Result<Value, ShellError> {
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use ast::*;
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match expr {
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Expression::Leaf(l) => Ok(evaluate_leaf(l)),
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Expression::Parenthesized(p) => evaluate_expr(&p.expr, scope),
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2019-05-31 07:45:57 +02:00
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Expression::Flag(f) => Err(ShellError::string(format!(
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"can't evaluate the flag {}",
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f.print()
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))),
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2019-05-28 08:45:18 +02:00
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Expression::Block(b) => evaluate_block(&b, scope),
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Expression::Path(p) => evaluate_path(&p, scope),
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Expression::Binary(b) => evaluate_binary(b, scope),
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Expression::VariableReference(r) => evaluate_reference(r, scope),
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}
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}
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fn evaluate_leaf(leaf: &ast::Leaf) -> Value {
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use ast::*;
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match leaf {
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Leaf::String(s) => Value::string(s),
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2019-05-30 06:19:46 +02:00
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Leaf::Bare(path) => Value::string(path.to_string()),
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2019-05-28 08:45:18 +02:00
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Leaf::Boolean(b) => Value::boolean(*b),
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Leaf::Int(i) => Value::int(*i),
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}
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}
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fn evaluate_reference(r: &ast::Variable, scope: &Scope) -> Result<Value, ShellError> {
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use ast::Variable::*;
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match r {
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It => Ok(scope.it.copy()),
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Other(s) => Err(ShellError::string(&format!(
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"Unimplemented variable reference: {}",
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s
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))),
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}
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}
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fn evaluate_binary(binary: &ast::Binary, scope: &Scope) -> Result<Value, ShellError> {
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let left = evaluate_expr(&binary.left, scope)?;
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let right = evaluate_expr(&binary.right, scope)?;
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match left.compare(binary.operator, &right) {
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Some(v) => Ok(Value::boolean(v)),
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None => Err(ShellError::string(&format!(
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"Unimplemented evaluate_binary:\n{:#?}",
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binary
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))),
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}
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}
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fn evaluate_block(block: &ast::Block, _scope: &Scope) -> Result<Value, ShellError> {
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Ok(Value::block(block.expr.clone()))
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}
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fn evaluate_path(path: &ast::Path, scope: &Scope) -> Result<Value, ShellError> {
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let head = path.head();
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let mut value = &evaluate_expr(head, scope)?;
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for name in path.tail() {
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let next = value.get_data_by_key(&name);
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match next {
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None => {
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return Err(ShellError::string(&format!(
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"No key {} found in {}",
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name,
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path.print(),
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)))
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}
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Some(v) => value = v,
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}
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}
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Ok(value.copy())
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}
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