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-rw-r--r--users/wpcarro/slx.js/index.js455
1 files changed, 455 insertions, 0 deletions
diff --git a/users/wpcarro/slx.js/index.js b/users/wpcarro/slx.js/index.js
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index 000000000000..3729978c75ef
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+++ b/users/wpcarro/slx.js/index.js
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+function select(query, xs, config) {
+    // naive optimizations
+    if (query === '' || xs === []) {
+        return xs;
+    }
+
+    const predicate = compile(parse(query, config), config);
+    return xs.filter(predicate);
+}
+
+function compile(ast, config) {
+    if (ast.type === 'CONJUNCTION') {
+        const lhs = compile(ast.lhs, compile);
+        const rhs = compile(ast.rhs, compile);
+
+        if (ast.joint === 'AND') {
+            return function(x) {
+                return lhs(x) && rhs(x);
+            };
+        }
+        if (ast.joint === 'OR') {
+            return function(x) {
+                return lhs(x) || rhs(x);
+            };
+        }
+    }
+    if (ast.type === 'DATE_SELECTION') {
+        if (ast.key === 'before') {
+            return function(row) {
+                let t = new Date();
+                if (ast.val === 'yesterday') {
+                    t.setDate(t.getDate() - 1);
+                    console.log(t);
+                }
+                // MM/DD/YYYY
+                else {
+                    t = new Date(ast.val);
+                }
+                return row[config.dateKey] < t;
+            };
+        }
+        if (ast.key === 'after') {
+            return function(row) {
+                let t = new Date();
+                if (ast.val === 'yesterday') {
+                    t.setDate(t.getDate() - 1);
+                    console.log(t);
+                }
+                // MM/DD/YYYY
+                else {
+                    t = new Date(ast.val);
+                }
+                return row[config.dateKey] > t;
+            };
+        }
+    }
+    if (ast.type === 'COMPARE_SELECTION') {
+        const f = compile(ast.val, config);
+
+        let compare = null;
+        if (ast.operator === 'EQ') { compare = (x, y) => x === y; }
+        if (ast.operator === 'LT') { compare = (x, y) => x < y; }
+        if (ast.operator === 'GT') { compare = (x, y) => x > y; }
+        if (ast.operator === 'LTE') { compare = (x, y) => x <= y; }
+        if (ast.operator === 'GTE') { compare = (x, y) => x >= y; }
+
+        return function(row) {
+            return ast.negate ? !compare(row[ast.key], ast.val) : compare(row[ast.key], ast.val);
+        };
+    }
+    if (ast.type === 'SELECTION') {
+        const f = compile(ast.val, config);
+        return function(row) {
+            return ast.negate ? !f(row[ast.key]) : f(row[ast.key]);
+        };
+    }
+    if (ast.type === 'MATCH_ALL') {
+        if (ast.matchType === 'STRING') {
+            return function(row) {
+                return Object.values(row).some(x => {
+                    if (config.caseSensitive) {
+                        return x === ast.val;
+                    } else {
+                        return x.toLowerCase() === ast.val.toLowerCase();
+                    }
+                })
+            };
+        }
+        if (ast.matchType === 'REGEX') {
+            return function(row) {
+                return Object.values(row).some(x => ast.val.test(x));
+            };
+        }
+    }
+    if (ast.type === 'GROUPING') {
+        return compile(ast.content);
+    }
+    if (ast.type === 'STRING') {
+        return function(x) {
+            if (config.caseSensitive) {
+                return x === ast.val;
+            } else {
+                return x.toLowerCase() === ast.val.toLowerCase();
+            }
+        };
+    }
+    if (ast.type === 'REGEX') {
+        return function(x) {
+            return ast.val.test(x);
+        };
+    }
+}
+
+// A "selection" without a "$column:" prefix should fuzzy-search all columns.
+//
+// conjunction -> selection ( ( "AND" | "OR" )? selection )* ;
+// selection   -> "-"? COLUMN ":" ( regex | string ) | regex ;
+// regex       -> [_-a-zA-Z0-9] | "/" [ _-a-zA-Z0-9] "/" | string ;
+// string      -> "\"" [ _-a-zA-Z0-9] "\"" ;
+
+// Whatever characters are valid for a JS regex.
+const ATOM_REGEX = /[-_.\[\]a-zA-Z0-9*+^$]/;
+
+function tokenize(x) {
+    const result = [];
+    let i = 0;
+    while (i < x.length) {
+        if (x[i] === ' ') {
+            i += 1;
+            while (i < x.length && x[i] === ' ') {
+                i += 1;
+            }
+            result.push(['WHITESPACE', null]);
+            continue;
+        }
+        if (x[i] === '-') {
+            result.push(['NEGATE', null]);
+            i += 1;
+            continue;
+        }
+        // Tokenize numbers (i.e. integers, floats).
+        if (/[0-9]/.test(x[i])) {
+            let curr = x[i];
+            i += 1;
+            while (i < x.length && /[0-9]/.test(x[i])) {
+                curr += x[i];
+                i += 1;
+            }
+            result.push(['NUMBER', parseFloat(curr)]);
+            continue;
+        }
+        if (ATOM_REGEX.test(x[i])) {
+            let curr = x[i];
+            i += 1;
+            while (i < x.length && ATOM_REGEX.test(x[i])) {
+                curr += x[i];
+                i += 1;
+            }
+            result.push(['ATOM', curr]);
+            continue;
+        }
+        if (x[i] === '=') {
+            result.push(['COMPARE', 'EQ']);
+            i += 1;
+            continue;
+        }
+        if (x[i] === '<' && i + 1 < x.length && x[i + 1] === '=') {
+            result.push(['COMPARE', 'LTE']);
+            i += 2;
+            continue;
+        }
+        if (x[i] === '<') {
+            result.push(['COMPARE', 'LT']);
+            i += 1;
+            continue;
+        }
+        if (x[i] === '>' && i + i < x.length && x[i + 1] === '=') {
+            result.push(['COMPARE', 'GTE']);
+            i += 2;
+            continue;
+        }
+        if (x[i] === '>') {
+            result.push(['COMPARE', 'GT']);
+            i += 1;
+            continue;
+        }
+        if (x[i] === ':') {
+            result.push(['COLON', null]);
+            i += 1;
+            continue;
+        }
+        if (x[i] === '(') {
+            result.push(['LPAREN', null]);
+            i += 1;
+            continue;
+        }
+        if (x[i] === ')') {
+            result.push(['RPAREN', null]);
+            i += 1;
+            continue;
+        }
+        if (x[i] === '/') {
+            let start = i;
+            let curr = '';
+            i += 1;
+            while (i < x.length && x[i] !== '/') {
+                curr += x[i];
+                i += 1;
+            }
+            // error
+            if (i >= x.length) {
+                throw `Tokenize Error: EOL while attempting to tokenize the regex beginning at column: ${start}`;
+            }
+            if (x[i] === '/') {
+                result.push(['REGEX', curr]);
+                i += 1;
+            }
+            continue;
+        }
+        if (x[i] === '"') {
+            let start = i;
+            let curr = '';
+            i += 1;
+            while (i < x.length && x[i] !== '"') {
+                // continue on \"
+                if (x[i] === '\\' && x[i + 1] === '"') {
+                    curr += '\"';
+                    i += 2;
+                } else {
+                    curr += x[i];
+                    i += 1;
+                }
+            }
+            if (i >= x.length) {
+                throw `Tokenize Error: EOL while attempting to tokenize the string starting at column: ${start}`;
+            }
+            if (x[i] === '"') {
+                result.push(['STRING', curr]);
+                i += 1;
+            }
+            continue;
+        }
+        else {
+            i += 1;
+        }
+    }
+    return result;
+}
+
+function expect(f, expectation, p) {
+    const [type, val] = p.tokens[p.i];
+    if (f(type, val)) {
+        p.i += 1;
+    } else {
+        throw `Parse Error: expected ${expectation}, but got ${p.tokens[p.i]}; ${JSON.stringify(p)}`
+    }
+}
+
+function matches(f, p) {
+    const [type, val] = p.tokens[p.i];
+    if (f(type, val)) {
+        return true;
+    }
+    return false;
+}
+
+function match(f, expectation, p) {
+    const [type, val] = p.tokens[p.i];
+    if (f(type, val)) {
+        p.i += 1;
+        return val;
+    }
+    throw `Parse Error: expected ${expectation}, but got: ${p.tokens[p.i]}; ${JSON.stringify(p)}`;
+}
+
+function skipWhitespace(p) {
+    while (p.i < p.tokens.length && matches((type, _) => type === 'WHITESPACE', p)) {
+        p.i += 1;
+    }
+}
+
+function peekType(n, p) {
+    if (p.i + n < p.tokens.length) {
+        return p.tokens[p.i + n][0];
+    }
+    return null;
+}
+
+function parser(tokens) {
+    return { i: 0, tokens };
+}
+
+function parse(x, config) {
+    const tokens = tokenize(x);
+    const p = parser(tokens);
+    return conjunction(p, config);
+}
+
+function conjunction(p, config) {
+    skipWhitespace(p);
+
+    const lhs = selection(p, config);
+    skipWhitespace(p);
+
+    // TODO(wpcarro): Consider re-architecting the parser to avoid smells like
+    // this.
+    if (peekType(0, p) === 'RPAREN') {
+        return lhs;
+    }
+
+    if (p.i >= p.tokens.length) {
+        return lhs;
+    }
+
+    let joint = 'AND';
+    if (matches((type, val) => type === 'ATOM' && val === 'AND', p)) {
+        joint = 'AND';
+        p.i += 1;
+    } else if (matches((type, val) => type === 'ATOM' && val === 'OR', p)) {
+        joint = 'OR';
+        p.i += 1;
+    }
+    skipWhitespace(p);
+    const rhs = conjunction(p, config);
+
+    return {
+        type: 'CONJUNCTION',
+        joint,
+        lhs,
+        rhs,
+    };
+}
+
+function selection(p, config) {
+    // column:value OR -column:value
+    if ((peekType(0, p) === 'ATOM' && peekType(1, p) === 'COLON') ||
+        (peekType(0, p) === 'NEGATE' && peekType(1, p) === 'ATOM' && peekType(2, p) === 'COLON')) {
+
+        let negate = false;
+        if (p.tokens[p.i][0] === 'NEGATE') {
+            negate = true;
+            p.i += 1;
+        }
+
+        const key = match((type, _) => type === 'ATOM', 'a column label', p);
+        expect((type, val) => type === 'COLON', 'a colon', p);
+
+        if (key === 'before' || key === 'after') {
+            const val = date(p);
+            return {
+                type: 'DATE_SELECTION',
+                key,
+                val,
+            };
+        } else {
+            const val = value(p, config);
+            return {
+                type: 'SELECTION',
+                negate,
+                key,
+                val,
+            };
+        }
+    }
+    // column<value OR -column<value
+    else if ((peekType(0, p) === 'ATOM' && peekType(1, p) === 'COMPARE') ||
+             (peekType(0, p) === 'NEGATE' && peekType(1, p) === 'ATOM' && peekType(2, p) === 'COMPARE')) {
+        let negate = false;
+        if (p.tokens[p.i][0] === 'NEGATE') {
+            negate = true;
+            p.i += 1;
+        }
+
+        const key = match((type, _) => type === 'ATOM', 'a column label', p);
+        const operator = match((type, _) => type === 'COMPARE', 'a comparison operator (i.e. "<", ">", "<=", ">=")', p);
+        const val = match((type, _) => type === 'NUMBER', 'a number', p);
+
+        return {
+            type: 'COMPARE_SELECTION',
+            operator,
+            negate,
+            key,
+            val,
+        };
+    }
+    else {
+        return matchAll(p, config);
+    }
+}
+
+function matchAll(p, config) {
+    const [type, val] = p.tokens[p.i];
+
+    // Cast atoms into strings or regexes depending on the current config.
+    if (type === 'ATOM') {
+        p.i += 1;
+        if (config.preferRegex) {
+            const regex = config.caseSensitive ? new RegExp(val) : new RegExp(val, "i");
+            return { type: 'MATCH_ALL', matchType: 'REGEX', val: regex };
+        } else {
+            return { type: 'MATCH_ALL', matchType: 'STRING', val }
+        }
+    }
+    if (type === 'STRING') {
+        p.i += 1;
+        return { type: 'MATCH_ALL', matchType: 'STRING', val };
+    }
+    if (type === 'REGEX') {
+        p.i += 1;
+        const regex = config.caseSensitive ? new RegExp(val) : new RegExp(val, "i");
+        return { type: 'MATCH_ALL', matchType: 'REGEX', val: regex };
+    }
+    if (type === 'LPAREN') {
+        p.i += 1;
+        const content = conjunction(p, config);
+        expect((type, _) => type === 'RPAREN', 'a closing parenthesis', p);
+        return {
+            type: 'GROUPING',
+            content,
+        };
+    }
+    throw `Parse Error: Expected a regular expression or a string, but got: ${p.tokens[p.i]}; ${JSON.stringify(p)}`;
+}
+
+function value(p, config) {
+    const [type, val] = p.tokens[p.i];
+
+    // Cast atoms into strings or regexes depending on the current config.
+    if (type === 'ATOM') {
+        p.i += 1;
+        if (config.preferRegex) {
+            const regex = config.caseSensitive ? new RegExp(val) : new RegExp(val, "i");
+            return { type: 'REGEX', val: regex };
+        } else {
+            return { type: 'STRING', val }
+        }
+    }
+    if (type === 'STRING') {
+        p.i += 1;
+        return { type, val };
+    }
+    if (type === 'REGEX') {
+        p.i += 1;
+        const regex = config.caseSensitive ? new RegExp(val) : new RegExp(val, "i");
+        return { type, val: regex };
+    }
+    throw `Parse Error: Expected a regular expression or a string, but got: ${p.tokens[p.i]}; ${JSON.stringify(p)}`;
+}
+
+function date(p) {
+    const [type, val] = p.tokens[p.i];
+    p.i += 1;
+
+    return val;
+}