# All files parser.js

90.28% Statements 195/216
80% Branches 48/60
74.42% Functions 32/43
93.26% Lines 180/193

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     var Parser = function(token_types){
        var self = this;
        this.token_types = token_types;
        this.symbol_table = {};

        this.original_symbol = {
            nud: function () { throw Error("Undefined"); },
            led: function () { throw Error("Missing operator"); }
        };

        this.mul = function(left){ return ["*", [left, this.nud()]]; };

        this.symbol = function (id, bp) {
            var s = self.symbol_table[id];
            bp = bp || 0;
            if (s) {
                if (bp >= s.lbp) {
                    s.lbp = bp;
                }
            } else {
                s = Object.create(self.original_symbol);
                s.id = s.value = id;
                s.lbp = bp;
                s.parent = self;
                self.symbol_table[id] = s;
            }
            return s;
        };

        this.advance = function (id) {
            var a, o, t, v;
            Iif (id && this.token.id !== id) {
                throw Error("Expected '" + id + "'");
            }
            if (self.token_nr >= self.tokens.length) {
                self.token = this.symbol_table["(end)"];
                return;
            }
            t = self.tokens[self.token_nr];
            self.token_nr += 1;
            v = t.value;
            var args = null;
            a = t.type;
            if (a === "name") {
                o = this.symbol_table["(var)"];
            } else if (a === "operator") {
                o = this.symbol_table[v];
                Iif (!o) {
                    throw Error("Unknown operator");
                }
            } else if (a === "pass") {
                a = "pass";
                o = this.symbol_table["(pass)"];
                args = t.args;
            } else if (a === "number") {
                a = "literal";
                o = this.symbol_table["(literal)"];
            } else Eif (a === "function") {
                a = "function";
                o = this.symbol_table["(function)"];
                args = t.args;
            } else {
                throw Error("Unexpected token",t);
            }
            self.token = Object.create(o);
            self.token.type = a;
            self.token.value = v;
            if(args) self.token.args = args;
            return self.token;
        };

        this.expression = function (rbp) {
            var left;
            var t = self.token;
            self.advance();
            left = t.nud();
            while (rbp < self.token.lbp) {
                t = self.token;
                self.advance();
                left = t.led(left);
            }
            return left;
        };

        this.infix = function (id, bp, led) {
            var s = this.symbol(id, bp);
            s.led = led || function (left) {
                return [this.value, [left, self.expression(bp)]];
            };
            return s;
        };

        this.prefix = function (id, nud) {
            var s = self.symbol(id);
            s.nud = nud || function () {
                Eif(this.value == "-") this.value = "neg";
                return [this.value, [self.expression(70)]];
            };
            return s;
        }

        this.symbol("(end)");
        var s = null;

        s = this.symbol("(blank)", 60);
        s.nud = function(){ return ["blank"];};

        s = this.symbol("(function)", 60);
        s.led = this.mul;
        s.nud = function(){ return [this.value, this.args || []];};

        s = this.symbol("(literal)", 60);
        s.led = this.mul;
        s.nud = function(){ return ["val", [this.value]] };

        s = this.symbol("(pass)", 60);
        s.led = this.mul;
        s.nud = function(){ return this.args[0] };

        s = this.symbol("(var)", 60);
        s.led = this.mul;
        s.nud = function(){ return ["var", [this.value]] };

        this.token_nr = 0;
        this.tokens = [];

        this.infix("=", 40);
        this.infix("!=", 40);
        this.infix("<", 40);
        this.infix(">", 40);
        this.infix("<=", 40);
        this.infix(">=", 40);
        this.infix("+", 50);
        this.infix("-", 50);
        this.infix("*", 60);
        this.infix("/", 60);
        this.infix("!", 70, function(left){ return ["factorial", [left]]; });
        this.infix("^", 70, function(left){ return ["exponential", [left, self.expression(70)]]; });
        this.infix("_", 70, function(left){ return ["subscript", [left, self.expression(70)]]; });
        this.infix("(", 80, self.mul);
        this.symbol("(").nud = function(){ var ans = self.expression(0); self.advance(")"); return ans; }
        this.symbol(")");
        this.symbol("{").nud = function(){ var ans = self.expression(0); self.advance("}"); return ans; }
        this.symbol("}");
        this.symbol(",");
        this.prefix("-");

        this.tokenise_and_parse = function(str){
            return this.parse(this.tokenise(str));
        }

        this.parse = function(tokens){
            this.tokens = tokens;
            this.token_nr = 0;
            Iif(this.tokens.length == 0) return ["blank"];
            this.advance();
            return this.expression(10);
        }
    }

    Parser.prototype.tokenise = function(text){
        var ans = [];
        while(text.length > 0){
            var ok = false;
            for(var i = 0; i < this.token_types.length; i++){
                var t = this.token_types[i];
                var re = RegExp(t.re);
                var m = re.exec(text);
                if(m){
                    m = m[0];
                    text = text.substring(m.length);
                    ok = true;
                    Eif(t.type != "space") ans.push({"type":t.type, "value": t.value(m)})
                    break;
                }
            }
            if(!ok){
                Eif(text.charCodeAt(0) > 128){
                    var c = "";
                    for(var ch of text){
                        c = ch;
                        break;
                    }
                    ans.push({"type":"name", "value":c});
                    text = text.substring(c.length);
                }
                else{
                    return [];
                }
            }
        }
        return ans;
    }

    var EParser = new Parser([
        {"type":"number", "re":"^[0-9.]+", "value":function(m){
            Iif(isNaN(Number(m))) throw Error("Invalid number: "+m);
            return Number(m);
        }},
        {"type":"operator", "re":"^(<=|>=|!=|>|<|=)", "value":function(m){return m}},
        {"type":"operator", "re":"^[-+*/!]", "value":function(m){return m}},
        {"type":"name", "re":"^[a-zA-Z]", "value":function(m){return m}},
        {"type":"space", "re":"^\\s+", "value":function(m){return m}}
    ]);

    var TextParser = new Parser([
        {"type":"number", "re":"^[0-9.]+", "value":function(m){
            Iif(isNaN(Number(m))) throw Error("Invalid number: "+m);
            return Number(m);
        }},
        {"type":"operator", "re":"^(!=|>=|<=)", "value":function(m){return m;}},
        {"type":"operator", "re":"^[-+*/,!()=<>_^]", "value":function(m){return m}},
        {"type":"name", "re":"^[a-zA-Z_]*[a-zA-Z]", "value":function(m){return m}},
        {"type":"comma", "re":"^,", "value":function(m){return m}},
        {"type":"space", "re":"^\\s+", "value":function(m){return m}}
    ]);

    var s = TextParser.symbol("(var)", 60);
    s.led = TextParser.mul;
    s.nud = function(){
        if(this.parent.token.id == "("){
            var args = [];
            TextParser.advance()
            if(this.parent.token.id !== ")"){
                while(true){
                    args.push(TextParser.expression(0));
                    if (this.parent.token.id !== ",") {
                        break;
                    }
                    TextParser.advance(",");
                }
            }
            TextParser.advance(")");
            return [this.value, args];
        }
        else{
            return ["var", [this.value]]
        }
    };

    var LaTeXParser = new Parser([
        {"type":"number", "re":"^[0-9.]+", "value":function(m){
            Iif(isNaN(Number(m))) throw Error("Invalid number: "+m);
            return Number(m);
        }},
        {"type":"operator", "re":"^(!=|>=|<=)", "value":function(m){return m;}},
        {"type":"operator", "re":"^[-+*/,!()=<>_^}{]", "value":function(m){return m}},
        {"type":"name", "re":"^[a-zA-Z_]*[a-zA-Z]", "value":function(m){return m}},
        {"type":"name", "re":"^\\\\[a-zA-Z]*[a-zA-Z]", "value":function(m){return m.substring(1)}},
        {"type":"space", "re":"^\\s+", "value":function(m){return m}}
    ]);

    s = LaTeXParser.symbol("(var)", 60);
    s.led = LaTeXParser.mul;
    s.nud = function(){
        var args = [];

        while(this.parent.token.id == "{"){
            LaTeXParser.advance()
            Eif(this.parent.token.id !== "}"){
                args.push(LaTeXParser.expression(0));
                LaTeXParser.advance("}");
            }
        }
        if(args.length > 0) return [this.value, args];
        else return ["var", [this.value]]
    };

    export default {"Parser":Parser,
                    "TextParser":TextParser,
                    "LaTeXParser":LaTeXParser,
                    "EParser": EParser};