summaryrefslogtreecommitdiff
path: root/dhall/src/phase/resolve.rs
blob: c4d7e5f5c836e7330b6194d8f10fb0fd9cbb4847 (plain)
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
use std::collections::HashMap;
use std::path::{Path, PathBuf};

use dhall_syntax::Import;

use crate::error::{Error, ImportError};
use crate::phase::{Normalized, Parsed, Resolved};

/// A root from which to resolve relative imports.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ImportRoot {
    LocalDir(PathBuf),
}

type ImportCache = HashMap<Import, Normalized>;

pub type ImportStack = Vec<Import>;

fn resolve_import(
    import: &Import,
    root: &ImportRoot,
    import_cache: &mut ImportCache,
    import_stack: &ImportStack,
) -> Result<Normalized, ImportError> {
    use self::ImportRoot::*;
    use dhall_syntax::FilePrefix::*;
    use dhall_syntax::ImportLocation::*;
    let cwd = match root {
        LocalDir(cwd) => cwd,
    };
    match &import.location_hashed.location {
        Local(prefix, path) => {
            let path: PathBuf = path.iter().cloned().collect();
            let path = match prefix {
                // TODO: fail gracefully
                Parent => cwd.parent().unwrap().join(path),
                Here => cwd.join(path),
                _ => unimplemented!("{:?}", import),
            };
            Ok(load_import(&path, import_cache, import_stack).map_err(|e| {
                ImportError::Recursive(import.clone(), Box::new(e))
            })?)
        }
        _ => unimplemented!("{:?}", import),
    }
}

fn load_import(
    f: &Path,
    import_cache: &mut ImportCache,
    import_stack: &ImportStack,
) -> Result<Normalized, Error> {
    Ok(
        do_resolve_expr(Parsed::parse_file(f)?, import_cache, import_stack)?
            .typecheck()?
            .normalize(),
    )
}

fn do_resolve_expr(
    Parsed(expr, root): Parsed,
    import_cache: &mut ImportCache,
    import_stack: &ImportStack,
) -> Result<Resolved, ImportError> {
    let resolve = |import: &Import| -> Result<Normalized, ImportError> {
        if import_stack.contains(import) {
            return Err(ImportError::ImportCycle(
                import_stack.clone(),
                import.clone(),
            ));
        }
        match import_cache.get(import) {
            Some(expr) => Ok(expr.clone()),
            None => {
                // Copy the import stack and push the current import
                let mut import_stack = import_stack.clone();
                import_stack.push(import.clone());

                // Resolve the import recursively
                let expr =
                    resolve_import(import, &root, import_cache, &import_stack)?;

                // Add the import to the cache
                import_cache.insert(import.clone(), expr.clone());
                Ok(expr)
            }
        }
    };
    let expr = expr.traverse_embed(resolve)?;
    Ok(Resolved(expr))
}

pub fn resolve(e: Parsed) -> Result<Resolved, ImportError> {
    do_resolve_expr(e, &mut HashMap::new(), &Vec::new())
}

pub fn skip_resolve_expr(
    Parsed(expr, _root): Parsed,
) -> Result<Resolved, ImportError> {
    let resolve = |import: &Import| -> Result<Normalized, ImportError> {
        Err(ImportError::UnexpectedImport(import.clone()))
    };
    let expr = expr.traverse_embed(resolve)?;
    Ok(Resolved(expr))
}

#[cfg(test)]
mod spec_tests {
    #![rustfmt::skip]

    macro_rules! import_success {
        ($name:ident, $path:expr) => {
            make_spec_test!(Import, Success, $name, &("success/".to_owned() + $path));
        };
    }

    // macro_rules! import_failure {
    //     ($name:ident, $path:expr) => {
    //         make_spec_test!(Import, Failure, $name, &("failure/".to_owned() + $path));
    //     };
    // }

    // import_success!(success_alternativeEnvNatural, "alternativeEnvNatural");
    // import_success!(success_alternativeEnvSimple, "alternativeEnvSimple");
    // import_success!(success_alternativeNatural, "alternativeNatural");
    // import_success!(success_asText, "asText");
    import_success!(success_fieldOrder, "fieldOrder");
    // import_failure!(failure_alternativeEnv, "alternativeEnv");
    // import_failure!(failure_alternativeEnvMissing, "alternativeEnvMissing");
    // import_failure!(failure_cycle, "cycle");
    // import_failure!(failure_missing, "missing");
    // import_failure!(failure_referentiallyInsane, "referentiallyInsane");
}