X-Git-Url: https://git.kianting.info/?a=blobdiff_plain;f=src%2Findex.ts;h=e22fdbbdd6550fe81c5779546472dd388927d95a;hb=c236ca23a513d0a456add8c98401af10cfbdb295;hp=3c3384d520bc8bf8d6e54bd6f00bbf47cf909ee2;hpb=6aa3c9a604ffd40cc0d3fdfa75bc575170e15044;p=clo

diff --git a/src/index.ts b/src/index.ts
index 3c3384d..e22fdbb 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,8 +1,17 @@
 var fs = require('fs');
 
-type Some<T> = { _tag: "Some"; value: T };
-type None = {_tag: "None"};
+export type Some<T> = { _tag: "Some"; value: T };
+export type None = {_tag: "None"};
 
+
+/**
+ * wrap a x in a `Some(T)`
+ * @param x : variable to be wrapped.
+ * @returns wrapped `x`.
+ */
+function toSome<T>(x: T): Some<T>{
+    return  { _tag: "Some", value: x};  
+}
 /**
  * @description Like the `Some(a)` and `None` in Rust.
  *
@@ -33,6 +42,9 @@ export type MatcheePair = {matched : string; remained : string};
  */
 export function match1Char(c : string) : (m: MatcheePair) => Maybe<MatcheePair> {
     return (m : MatcheePair)=>{
+        if (m.remained.length == 0){
+            return { _tag: "None" };
+        }
         const charToBeMatched = m.remained[0];
         if (charToBeMatched === c){
             return {_tag: "Some", value :{
@@ -45,6 +57,54 @@ export function match1Char(c : string) : (m: MatcheePair) => Maybe<MatcheePair>
     }
 };
 
+/**
+ * 
+ * @param m : the `MatcheePair` to be consumed.
+ * @returns if the length of `m.remained` >= 1; consumes the matchee by 1 char and wraps it in `Some`,
+ * otherwise, returns `None`.
+ */
+export function matchAny(m : MatcheePair) : Maybe<MatcheePair>{
+    if (m.remained.length >= 1){
+        return {_tag: "Some", value :{
+            matched : m.matched + m.remained[0],
+            remained : m.remained.substring(1)}};
+    }else{
+        return {_tag: "None"};
+    }
+}
+
+/**
+ * @description
+ * it returns a function which test if the first char of the `remained` part of
+ *  the argument of the function is between `l` and `u`, if it's true, update the `MatchedPair` wrapped
+ * in `Some`. Otherwise, it returns `None`.
+ *  * @param l : lower bound char, 1-char string
+ *  * @param u : upper bound char, 1-char string
+ * @returns the updated `MatchedPair` wrapped in `Some(x)` or `None`.
+ */
+export function matchRange(l : string, u : string) : (m: MatcheePair) => Maybe<MatcheePair> {
+    let lCodepoint = charToCodepoint(l);
+    let uCodepoint = charToCodepoint(u);
+    if (l > u){
+        throw new Error("Error: the codepoint of `"+l+"` is not smaller than `"+u+"`)");
+    }
+    return (m : MatcheePair)=>{
+        if (m.remained.length < 1){
+            return {_tag : "None"};
+        }
+        const charToBeMatched = m.remained[0];
+        const codePointToBeMatched = charToCodepoint(charToBeMatched);
+        if (codePointToBeMatched >= lCodepoint && codePointToBeMatched <= uCodepoint){
+            return {_tag: "Some", value :{
+                    matched : m.matched + charToBeMatched,
+                    remained : m.remained.substring(1)}};
+        }
+        else{
+            return {_tag: "None"};
+        }
+    }
+};
+
 /**
  * convert the one-char string to codepoint.
  * @param s : the string to code point.
@@ -62,6 +122,10 @@ export function charToCodepoint(s : string): number{
 /**
  *  @description thendo(input, f, ...) like
  * a ==> f
+ * @param input: the wrapped input. 
+ * @param f: the function to be applied.
+ * 
+ * @returns:the applied wrapped result `MatcheePair`.
  */
 export function thenDo<T>(input : Maybe<T>, f : Function) : Maybe<T>{
     if (input._tag == "None"){
@@ -72,3 +136,118 @@ export function thenDo<T>(input : Maybe<T>, f : Function) : Maybe<T>{
         return f(inner);
     }
 }
+
+/**
+ * @description "or", like the regex `( f1 | f2 )` . 
+ * It returns a function `f` of which the argument is`x`.
+ * if `f1(x)` is None, then `f` returns `f2(x)`. Otherwise, 
+ * `F` returns `f1(x)`.
+ * @param f1 : 1st function to be compared
+ * @param f2 : 2nd function to be compared
+ * @returns:the combined function
+ */
+export function orDo<T>(f1 : Function, f2: Function) : (x : T ) => Maybe<T>{
+    return (x) => {
+        let f1x : Maybe<T> = (f1(x));
+        {
+            if (f1x._tag == "None"){
+                return f2(x);
+            }
+            else{
+                return f1x;
+            }
+        }
+    };
+}
+
+
+/**
+* @description repeating matching function `f` 
+* zero or more times, like the asterisk `*` in regex `f*` . 
+* @param f : the function to be repeated 0+ times.
+* @returns:the combined function
+*/
+export function zeroOrMoreDo<T>(f : Function): (x : T) => Maybe<T>{
+    return (x)=>{
+        var wrapped_old_x : Maybe<T> = {_tag: "Some", value : x};
+        var wrapped_new_x : Maybe<T> = wrapped_old_x;
+
+        while (wrapped_new_x._tag != "None"){
+            wrapped_old_x = wrapped_new_x;
+            wrapped_new_x = thenDo(wrapped_old_x, f);
+        };
+
+        return wrapped_old_x;
+    };
+}
+
+/**
+* @description Not. like the `^` inside regex of [^f].
+* returns a function `F(x)` such that if  `f(x)` is `None`,
+* returns the x consuming a char; if `f(x)` is not None, F(x)
+* returns `None`.
+* @param f: the function forbidden to be matched.
+* @returns: combined function `F`.
+*/
+export function notDo<T>(f : Function): (x : T) => Maybe<T>{
+    return (x)=>{
+        let wrapped_x : Maybe<T> = {
+            _tag : "Some",
+            value : x
+        };
+        let f_x = thenDo(wrapped_x, f);
+        
+        if (f_x._tag != "None"){
+            return {_tag:"None"};
+        }else{
+            return thenDo(wrapped_x, matchAny);
+        }
+    };
+}
+
+/**
+ * if `x` is matched by `f` once, returns `f(x)`. Otherwise, 
+ * returns x
+ * similar to `?` in regex `f?`.
+ * @param f : the function to be matched
+ * @returns return wrapped f(x)
+ */
+export function zeroOrOnceDo<T>(f : Function): (x : T) => Maybe<T>{
+    return (x)=>{
+        var wrapped_old_x : Maybe<T> = {_tag: "Some", value : x};
+        var wrapped_new_x = thenDo(wrapped_old_x, f);
+
+        if (wrapped_new_x._tag != "None"){
+            return wrapped_new_x;
+        }else{
+        return wrapped_old_x;
+        }
+    };
+}
+
+
+export function tokenize(input : string){
+    var input_matchee_pair : Maybe<MatcheePair> = toSome(
+        {matched:"",
+        remained: input});
+
+    // integer = ([+]|[-])\d\d?
+    let integer = (x : MatcheePair) => 
+    { let wrapped_x = toSome(x);
+        let plusMinus = orDo(match1Char('+'), match1Char('-')); // ([+]|[-])
+        let d = matchRange('0','9'); // \d
+        return thenDo(thenDo(thenDo(wrapped_x, 
+            zeroOrOnceDo(plusMinus)),d),
+            zeroOrMoreDo(d));
+    }
+    console.log(input+", result: ");
+    console.log(thenDo(input_matchee_pair, integer));
+    // TODO: id, string, space, basic operator, 3 marks: @, {, }.
+
+}
+
+tokenize("+123");
+tokenize("123");
+tokenize("-123");
+tokenize(" 123");
+tokenize("c123");
\ No newline at end of file