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Make if blocks work like a def-env (#4656)

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* Make `if` work like a def-env

* Add some tests

* Add an example
This commit is contained in:
JT
2022-03-08 07:45:47 -05:00
committed by GitHub
parent ae7c0b1097
commit 477f3be8df
2 changed files with 70 additions and 14 deletions
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71
crates/nu-command/src/core_commands/if_.rs
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@ -37,50 +37,88 @@ impl Command for If {
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
caller_stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
let cond = &call.positional[0];
let then_block: CaptureBlock = call.req(engine_state, stack, 1)?;
let then_block: CaptureBlock = call.req(engine_state, caller_stack, 1)?;
let else_case = call.positional.get(2);
let result = eval_expression(engine_state, stack, cond)?;
let result = eval_expression(engine_state, caller_stack, cond)?;
match &result {
Value::Bool { val, .. } => {
if *val {
let block = engine_state.get_block(then_block.block_id);
let mut stack = stack.captures_to_stack(&then_block.captures);
eval_block(
let mut callee_stack = caller_stack.captures_to_stack(&then_block.captures);
let result = eval_block(
engine_state,
&mut stack,
&mut callee_stack,
block,
input,
call.redirect_stdout,
call.redirect_stderr,
)
);
let caller_env_vars = caller_stack.get_env_var_names(engine_state);
// remove env vars that are present in the caller but not in the callee
// (the callee hid them)
for var in caller_env_vars.iter() {
if !callee_stack.has_env_var(engine_state, var) {
caller_stack.remove_env_var(engine_state, var);
}
}
// add new env vars from callee to caller
for env_vars in callee_stack.env_vars {
for (var, value) in env_vars {
caller_stack.add_env_var(var, value);
}
}
result
} else if let Some(else_case) = else_case {
if let Some(else_expr) = else_case.as_keyword() {
if let Some(block_id) = else_expr.as_block() {
let result = eval_expression(engine_state, stack, else_expr)?;
let result = eval_expression(engine_state, caller_stack, else_expr)?;
let else_block: CaptureBlock = FromValue::from_value(&result)?;
let mut stack = stack.captures_to_stack(&else_block.captures);
let mut callee_stack =
caller_stack.captures_to_stack(&else_block.captures);
let block = engine_state.get_block(block_id);
eval_block(
let result = eval_block(
engine_state,
&mut stack,
&mut callee_stack,
block,
input,
call.redirect_stdout,
call.redirect_stderr,
)
);
let caller_env_vars = caller_stack.get_env_var_names(engine_state);
// remove env vars that are present in the caller but not in the callee
// (the callee hid them)
for var in caller_env_vars.iter() {
if !callee_stack.has_env_var(engine_state, var) {
caller_stack.remove_env_var(engine_state, var);
}
}
// add new env vars from callee to caller
for env_vars in callee_stack.env_vars {
for (var, value) in env_vars {
caller_stack.add_env_var(var, value);
}
}
result
} else {
eval_expression(engine_state, stack, else_expr)
eval_expression(engine_state, caller_stack, else_expr)
.map(|x| x.into_pipeline_data())
}
} else {
eval_expression(engine_state, stack, else_case)
eval_expression(engine_state, caller_stack, else_case)
.map(|x| x.into_pipeline_data())
}
} else {
@ -112,6 +150,11 @@ impl Command for If {
example: "if 5 < 3 { 'yes!' } else if 4 < 5 { 'no!' } else { 'okay!' }",
result: Some(Value::test_string("no!")),
},
Example {
description: "Update the environment based on a condition",
example: r#"if true { let-env ENV_VAR = "new value" }"#,
result: None,
},
]
}
}