weld 0.4.0

Weld is a language and runtime for improving the performance of data-intensive applications.
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
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211

//! Compare expression trees ignoring Symbol values.

use fnv;

use super::ast::*;
use crate::error::*;

#[cfg(test)]
use crate::tests::*;

/// A trait for symbol-agnostic tree comparison.
pub trait CompareIgnoringSymbols {
    /// Compare this expression to `other`.
    ///
    /// Returns whether the two expressions are the same modulo symbol names.
    /// Returns an error if an undefined symbol is encountered.
    fn compare_ignoring_symbols(&self, other: &Self) -> WeldResult<bool>;
}

impl CompareIgnoringSymbols for Expr {
    /// Compare this expression to `other`.
    fn compare_ignoring_symbols(&self, other: &Expr) -> WeldResult<bool> {
        use self::ExprKind::*;
        use fnv::FnvHashMap;
        let mut sym_map: FnvHashMap<&Symbol, &Symbol> = FnvHashMap::default();
        let mut reverse_sym_map: FnvHashMap<&Symbol, &Symbol> = FnvHashMap::default();
        fn _compare_ignoring_symbols<'b, 'a>(
            e1: &'a Expr,
            e2: &'b Expr,
            sym_map: &mut FnvHashMap<&'a Symbol, &'b Symbol>,
            reverse_sym_map: &mut FnvHashMap<&'b Symbol, &'a Symbol>,
        ) -> WeldResult<bool> {
            // First, check the type.
            if e1.ty != e2.ty {
                return Ok(false);
            }
            // Check the kind of each expression. same_kind is true if each *non-expression* field
            // is equal and the kind of the expression matches. Also records corresponding symbol names.
            let same_kind = match (&e1.kind, &e2.kind) {
                (
                    &BinOp {
                        kind: ref kind1, ..
                    },
                    &BinOp {
                        kind: ref kind2, ..
                    },
                ) if kind1 == kind2 => Ok(true),
                (&UnaryOp { .. }, &UnaryOp { .. }) => Ok(true),
                (
                    &Cast {
                        kind: ref kind1, ..
                    },
                    &Cast {
                        kind: ref kind2, ..
                    },
                ) if kind1 == kind2 => Ok(true),
                (&ToVec { .. }, &ToVec { .. }) => Ok(true),
                (&Let { name: ref sym1, .. }, &Let { name: ref sym2, .. }) => {
                    sym_map.insert(sym1, sym2);
                    reverse_sym_map.insert(sym2, sym1);
                    Ok(true)
                }
                (
                    &Lambda {
                        params: ref params1,
                        ..
                    },
                    &Lambda {
                        params: ref params2,
                        ..
                    },
                ) => {
                    // Just compare types, and assume the symbol names "match up".
                    if params1.len() == params2.len()
                        && params1.iter().zip(params2).all(|t| t.0.ty == t.1.ty)
                    {
                        for (p1, p2) in params1.iter().zip(params2) {
                            sym_map.insert(&p1.name, &p2.name);
                            reverse_sym_map.insert(&p2.name, &p1.name);
                        }
                        Ok(true)
                    } else {
                        Ok(false)
                    }
                }
                (&NewBuilder(_), &NewBuilder(_)) => Ok(true),
                (&Negate(_), &Negate(_)) => Ok(true),
                (&Not(_), &Not(_)) => Ok(true),
                (&Broadcast(_), &Broadcast(_)) => Ok(true),
                (&MakeStruct { .. }, &MakeStruct { .. }) => Ok(true),
                (&MakeVector { .. }, &MakeVector { .. }) => Ok(true),
                (&Zip { .. }, &Zip { .. }) => Ok(true),
                (&GetField { index: idx1, .. }, &GetField { index: idx2, .. }) if idx1 == idx2 => {
                    Ok(true)
                }
                (&Length { .. }, &Length { .. }) => Ok(true),
                (&Lookup { .. }, &Lookup { .. }) => Ok(true),
                (&OptLookup { .. }, &OptLookup { .. }) => Ok(true),
                (&KeyExists { .. }, &KeyExists { .. }) => Ok(true),
                (&Slice { .. }, &Slice { .. }) => Ok(true),
                (&Sort { .. }, &Sort { .. }) => Ok(true),
                (&Merge { .. }, &Merge { .. }) => Ok(true),
                (&Res { .. }, &Res { .. }) => Ok(true),
                (
                    &For {
                        iters: ref liters, ..
                    },
                    &For {
                        iters: ref riters, ..
                    },
                ) => {
                    // If the iter kinds match for each iterator, the non-expression fields match.
                    Ok(liters
                        .iter()
                        .zip(riters.iter())
                        .all(|(ref l, ref r)| l.kind == r.kind))
                }
                (&If { .. }, &If { .. }) => Ok(true),
                (&Iterate { .. }, &Iterate { .. }) => Ok(true),
                (&Select { .. }, &Select { .. }) => Ok(true),
                (&Apply { .. }, &Apply { .. }) => Ok(true),
                (
                    &CUDF {
                        sym_name: ref sym_name1,
                        return_ty: ref return_ty1,
                        ..
                    },
                    &CUDF {
                        sym_name: ref sym_name2,
                        return_ty: ref return_ty2,
                        ..
                    },
                ) => {
                    let mut matches = sym_name1 == sym_name2;
                    matches = matches && return_ty1 == return_ty2;
                    Ok(matches)
                }
                (&Serialize(_), &Serialize(_)) => Ok(true),
                (
                    &Deserialize { ref value_ty, .. },
                    &Deserialize {
                        value_ty: ref value_ty2,
                        ..
                    },
                ) if value_ty == value_ty2 => Ok(true),
                (&Literal(ref l), &Literal(ref r)) if l == r => Ok(true),
                (&Ident(ref l), &Ident(ref r)) => {
                    if let Some(lv) = sym_map.get(l) {
                        Ok(**lv == *r)
                    } else if reverse_sym_map.contains_key(r) {
                        Ok(false) // r was defined in other expression but l wasn't defined in self.
                    } else {
                        Ok(*l == *r)
                    }
                }
                _ => Ok(false), // all else fail.
            };

            // Return if encountered and error or kind doesn't match.
            if same_kind.is_err() || !same_kind.as_ref().unwrap() {
                return same_kind;
            }

            // Recursively check the children.
            let e1_children: Vec<_> = e1.children().collect();
            let e2_children: Vec<_> = e2.children().collect();
            if e1_children.len() != e2_children.len() {
                return Ok(false);
            }
            for (c1, c2) in e1_children.iter().zip(e2_children) {
                let res = _compare_ignoring_symbols(&c1, &c2, sym_map, reverse_sym_map);
                if res.is_err() || !res.as_ref().unwrap() {
                    return res;
                }
            }
            Ok(true)
        }
        _compare_ignoring_symbols(self, other, &mut sym_map, &mut reverse_sym_map)
    }
}

#[test]
fn compare_expressions() {
    let e1 = parse_expr("for([1,2], appender, |e| e+1)").unwrap();
    let e2 = parse_expr("for([1,2], appender, |f| f+1)").unwrap();
    assert!(e1.compare_ignoring_symbols(&e2).unwrap());

    let e1 = parse_expr("let a = 2; a").unwrap();
    let e2 = parse_expr("let b = 2; b").unwrap();
    assert!(e1.compare_ignoring_symbols(&e2).unwrap());

    let e2 = parse_expr("let b = 2; c").unwrap();
    assert!(!e1.compare_ignoring_symbols(&e2).unwrap());

    // Undefined symbols should work as long as the symbol is the same.
    let e1 = parse_expr("[1, 2, 3, d]").unwrap();
    let e2 = parse_expr("[1, 2, 3, d]").unwrap();
    assert!(e1.compare_ignoring_symbols(&e2).unwrap());

    let e2 = parse_expr("[1, 2, 3, e]").unwrap();
    assert!(!e1.compare_ignoring_symbols(&e2).unwrap());

    // Symbols can be substituted, so equal.
    let e1 = parse_expr("|a, b| a + b").unwrap();
    let e2 = parse_expr("|c, d| c + d").unwrap();
    assert!(e1.compare_ignoring_symbols(&e2).unwrap());

    // Symbols don't match up.
    let e2 = parse_expr("|c, d| d + c").unwrap();
    assert!(!e1.compare_ignoring_symbols(&e2).unwrap());
}