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feat(sax): update error handling, add parse() wrapper, add FSMOpts
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- `unexpected()` does NOT throw error anymore,
  but triggers new ERROR FSM state
- add input `pos` counter to ParserState, use for error messages
- add `parse()` transducer wrapper
- update `fsm()` transducer to accept new `FSMOpts`
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@postspectacular
postspectacular committed Jun 17, 2018
1 parent a4766a5 commit 64f2378
Showing 1 changed file with 76 additions and 29 deletions.
105 changes: 76 additions & 29 deletions packages/sax/src/index.ts
View file
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
import { Event, IObjectOf } from "@thi.ng/api";
import { Transducer, Reducer } from "@thi.ng/transducers/api";
import { ensureReduced } from "@thi.ng/transducers/reduced";

export interface FSMState {
state: PropertyKey;
Expand All @@ -8,9 +9,16 @@ export interface FSMState {
export type FSMStateMap<T extends FSMState, A, B> = IObjectOf<FSMHandler<T, A, B>>;
export type FSMHandler<T extends FSMState, A, B> = (state: T, input: A) => B | void;

export function fsm<T extends FSMState, A, B>(states: FSMStateMap<T, A, B>, initial: () => T): Transducer<A, B> {
export interface FSMOpts<T extends FSMState, A, B> {
states: FSMStateMap<T, A, B>;
terminate: PropertyKey;
init: () => T;
}

export function fsm<T extends FSMState, A, B>(opts: FSMOpts<T, A, B>): Transducer<A, B> {
return (rfn: Reducer<any, B>) => {
let state = initial();
const states = opts.states;
const state = opts.init();
const r = rfn[2];
return [
rfn[0],
Expand All @@ -20,26 +28,17 @@ export function fsm<T extends FSMState, A, B>(states: FSMStateMap<T, A, B>, init
const res = states[<any>state.state](state, x);
if (res) {
acc = r(acc, res);
if (state.state == opts.terminate) {
return ensureReduced(acc);
}
}
return acc;
}];
}
}

const isWS = (x: string) =>
x == " " || x == "\t" || x == "\n" || x == "\r";

const isTagChar = (x: string) =>
(x >= "A" && x <= "Z") ||
(x >= "a" && x <= "z") ||
(x >= "0" && x <= "9") ||
x == "-" ||
x == "_" ||
x == ":";

const unexpected = (x) => { throw new Error(`unexpected char: ${x}`); };

export interface ParseState extends FSMState {
pos: number;
scope: any[];
tag: string;
body: string;
Expand All @@ -52,6 +51,7 @@ export interface ParseState extends FSMState {

enum State {
WAIT,
ERROR,
MAYBE_ELEM,
ELEM_START,
ELEM_END,
Expand All @@ -69,21 +69,54 @@ enum State {
PROC_END,
}

const isWS = (x: string) =>
x == " " || x == "\t" || x == "\n" || x == "\r";

const isTagChar = (x: string) =>
(x >= "A" && x <= "Z") ||
(x >= "a" && x <= "z") ||
(x >= "0" && x <= "9") ||
x == "-" ||
x == "_" ||
x == ":";

const unexpected = (s: ParseState, x: string) => {
s.state = State.ERROR;
return { id: "error", value: `unexpected char: '${x}' @ pos: ${s.pos}` };
};

export function parse() {
return fsm({
states: PARSER,
init: () => (<ParseState>{
state: State.WAIT,
scope: [],
pos: 0
}),
terminate: State.ERROR
});
}

export const PARSER: FSMStateMap<ParseState, string, Event> = {
[State.ERROR]: () => {
},

[State.WAIT]: (s: ParseState, x: string) => {
s.pos++;
if (!isWS(x)) {
if (x === "<") {
s.state = State.MAYBE_ELEM;
} else {
unexpected(x);
return unexpected(s, x);
}
}
},

[State.MAYBE_ELEM]: (s: ParseState, x: string) => {
s.pos++;
if (x === "/") {
if (s.scope.length == 0) {
unexpected(x);
return unexpected(s, x);
}
s.state = State.ELEM_END;
s.tag = "";
Expand All @@ -98,11 +131,12 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
s.phase = 0;
s.body = "";
} else {
unexpected(x);
return unexpected(s, x);
}
},

[State.ELEM_START]: (s: ParseState, x: string) => {
s.pos++;
if (isTagChar(x)) {
s.tag += x;
} else if (isWS(x)) {
Expand All @@ -116,11 +150,12 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
} else if (x === "/") {
s.state = State.ELEM_SINGLE;
} else {
unexpected(x);
return unexpected(s, x);
}
},

[State.ELEM_END]: (s: ParseState, x: string) => {
s.pos++;
if (isTagChar(x)) {
s.tag += x;
} else if (x === ">") {
Expand All @@ -140,6 +175,7 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
},

[State.ELEM_SINGLE]: (s: ParseState, x: string) => {
s.pos++;
if (x === ">") {
s.state = State.WAIT;
const n = s.scope.length;
Expand All @@ -149,11 +185,12 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
}
return { id: "elem", value: res };
} else {
unexpected(x);
return unexpected(s, x);
}
},

[State.ELEM_BODY]: (s: ParseState, x: string) => {
s.pos++;
if (x === "<") {
let res;
if (s.body.length > 0) {
Expand All @@ -169,6 +206,7 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
},

[State.MAYBE_ATTRIB]: (s: ParseState, x: string) => {
s.pos++;
if (isTagChar(x)) {
s.state = State.ATTRIB_NAME;
s.name = x;
Expand All @@ -184,30 +222,33 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
} else if (s.tag === "xml" && x === "?") {
s.state = State.PROC_END;
} else if (!isWS(x)) {
unexpected(x);
return unexpected(s, x);
}
},

[State.ATTRIB_NAME]: (s: ParseState, x: string) => {
s.pos++;
if (isTagChar(x)) {
s.name += x;
} else if (x === "=") {
s.state = State.ATTRIB_VAL_START;
} else {
unexpected(x);
return unexpected(s, x);
}
},

[State.ATTRIB_VAL_START]: (s: ParseState, x: string) => {
s.pos++;
if (x === "\"" || x === "'") {
s.state = State.ATTRIB_VALUE;
s.quote = x;
} else {
unexpected(x);
return unexpected(s, x);
}
},

[State.ATTRIB_VALUE]: (s: ParseState, x: string) => {
s.pos++;
if (x === s.quote) {
s.attribs[s.name] = s.val;
s.state = State.MAYBE_ATTRIB;
Expand All @@ -217,31 +258,34 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
},

[State.MAYBE_INSTRUCTION]: (s: ParseState, x: string) => {
s.pos++;
if (x === "-") {
s.state = State.COMMENT;
} else if (x === "D") {
s.state = State.DOCTYPE;
s.phase = 1;
s.body = "";
} else {
unexpected(x);
return unexpected(s, x);
}
},

[State.COMMENT]: (s: ParseState, x: string) => {
s.pos++;
if (x === "-") {
s.state = State.COMMENT_BODY;
s.body = "";
} else {
unexpected(x);
return unexpected(s, x);
}
},

[State.COMMENT_BODY]: (s: ParseState, x: string) => {
s.pos++;
if (x === ">") {
const n = s.body.length;
if (s.body.substr(n - 2) !== "--") {
unexpected(x);
return unexpected(s, x);
}
s.state = State.WAIT;
return { id: "comment", value: s.body.substr(0, n - 2) };
Expand All @@ -251,11 +295,12 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
},

[State.DOCTYPE]: (s: ParseState, x: string) => {
s.pos++;
if (s.phase < 8) {
if (x === "DOCTYPE "[s.phase]) {
s.phase++;
} else {
unexpected(x);
return unexpected(s, x);
}
} else if (x === ">") {
s.state = State.WAIT;
Expand All @@ -266,6 +311,7 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
},

[State.PROC_DECL]: (s: ParseState, x: string) => {
s.pos++;
if (x === "xml "[s.phase]) {
s.phase++;
if (s.phase == 4) {
Expand All @@ -274,16 +320,17 @@ export const PARSER: FSMStateMap<ParseState, string, Event> = {
s.attribs = {};
}
} else {
unexpected(x);
return unexpected(s, x);
}
},

[State.PROC_END]: (s: ParseState, x: string) => {
s.pos++;
if (x === ">") {
s.state = State.WAIT;
return { id: "proc", value: { tag: s.tag, attribs: s.attribs } };
} else {
unexpected(x);
return unexpected(s, x);
}
},
};

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