geam 0.1.1

Experimental Rust-embedded execution runtime for typed Gleam programs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162

use crate::plan::execution::explain::FunctionLabel;
use crate::plan::execution::explain::{Explain, ExplainContext};
use crate::plan::execution::function::NeverFunctionId;
use crate::plan::execution::graph::{NeverFunctionLocal, ParamLocal};

pub(crate) enum NeverCallTarget {
    Direct(NeverFunctionId),
    Value(NeverFunctionLocal),
}

pub(crate) struct NeverCall {
    function: NeverCallTarget,
    args: Box<[ParamLocal]>,
    site: crate::plan::HostCallSite,
}

impl NeverCall {
    pub(in crate::plan::execution) fn new(
        function: NeverCallTarget,
        args: Box<[ParamLocal]>,
        site: crate::plan::HostCallSite,
    ) -> Self {
        Self {
            function,
            args,
            site,
        }
    }

    pub(crate) fn function(&self) -> &NeverCallTarget {
        &self.function
    }

    pub(crate) fn args(&self) -> &[ParamLocal] {
        &self.args
    }

    pub(crate) fn site(&self) -> &crate::plan::HostCallSite {
        &self.site
    }
}

impl Explain for NeverCall {
    fn write_explanation(&self, context: &mut ExplainContext<'_, '_>) {
        context.push_str("never_call ");
        match self.function() {
            NeverCallTarget::Direct(function) => {
                FunctionLabel::new("never", function.0).write(context.output());
            }
            NeverCallTarget::Value(function) => context.write(function),
        }
        context.push_str(" args=");
        context.write_list(self.args(), |context, argument| context.write(argument));
    }
}

#[cfg(test)]
mod explain_tests {
    use super::super::Terminator;
    use super::NeverCall;
    use crate::plan::execution::explain;
    use crate::plan::execution::function::IntFunctionId;

    #[test]
    fn writes_direct_never_call() {
        let source = r#"
fn stop(value: Int) -> value { panic }

pub fn main() -> Int {
  let _ = stop(1)
  1
}
"#;
        let expected = "never_call never#0 args=[%int#0]";

        assert_explanation(source, expected);
    }

    #[test]
    fn writes_function_value_never_call() {
        let source = r#"
fn stop(value: Int) -> value { panic }

pub fn main() -> Int {
  let function = stop
  let _ = function(1)
  1
}
"#;
        let expected = "never_call %function.never#0 args=[%int#0]";

        assert_explanation(source, expected);
    }

    #[test]
    #[should_panic(expected = "source should lower one Never call")]
    fn never_call_shape_guard_is_visible() {
        explain::with_execution_plan("pub fn main() { 1 }", |plan| {
            never_call(&terminators(plan));
        });
    }

    #[test]
    #[should_panic(expected = "source should lower one Never call")]
    fn never_call_uniqueness_guard_is_visible() {
        let source = r#"
fn stop() -> value { panic }

pub fn main() -> Int {
  let _ = stop()
  1
}
"#;
        explain::with_execution_plan(source, |plan| {
            let call = never_call(&terminators(plan));
            never_call_from_nodes(&[call, call]);
        });
    }

    fn terminators(
        plan: &crate::plan::execution::ExecutionPlan,
    ) -> Vec<&crate::plan::execution::graph::Terminator> {
        plan.int_function(IntFunctionId(0))
            .body()
            .block_graph()
            .blocks()
            .iter()
            .map(|block| block.terminator())
            .collect()
    }

    fn never_call<'a>(terminators: &[&'a Terminator]) -> &'a NeverCall {
        let calls = terminators
            .iter()
            .copied()
            .filter_map(|terminator| match terminator {
                Terminator::NeverCall(call) => Some(call),
                _ => None,
            })
            .collect::<Vec<_>>();
        never_call_from_nodes(&calls)
    }

    fn never_call_from_nodes<'a>(calls: &[&'a NeverCall]) -> &'a NeverCall {
        let mut calls = calls.iter().copied();
        let Some(call) = calls.next() else {
            panic!("source should lower one Never call");
        };
        if calls.next().is_some() {
            panic!("source should lower one Never call");
        }
        call
    }

    fn assert_explanation(source: &str, expected: &str) {
        explain::assert_rendered(source, expected, |plan, output| {
            let call = never_call(&terminators(plan));
            let mut context = explain::ExplainContext::new(plan, output);
            context.write(call);
        });
    }
}