impl type transformers

Author: vytdev

src/sifter/index.ts

@@ -11,6 +11,7 @@ import type { CmdVerb } from './types.ts';
 
 export * from './parser.js';
 export * from './state.js';
+export * from './transforms.js';
 export type * from './types.ts';
 
 

src/sifter/transforms.ts

@@ -0,0 +1,104 @@
+import { ParseContext } from './state.js';
+import type { Transformer } from './types.ts';
+
+/**
+ * A raw string parser.
+ * @returns A cmd token transformer.
+ */
+export function stringType()
+{
+  return (ctx: ParseContext): string => {
+    return ctx.consumeToken();
+  };
+}
+
+/**
+ * A float parser.
+ * @returns A cmd token transformer.
+ */
+export function floatType()
+{
+  return (ctx: ParseContext): number => {
+    let tok = ctx.consumeToken();
+    const sign = tok[0] == '-' ? -1 : 1;
+    if ('+-'.includes(tok[0]))
+      tok = tok.slice(1);
+
+    if (tok == 'inf') return sign * Infinity;
+    if (tok == 'nan') return NaN;
+
+    if (!/^[0-9]*(\.[0-9]+)?$/.test(tok))
+      throw 'invalid float: ' + tok;
+
+    const val = parseFloat(tok);
+    if (isNaN(val))
+      throw 'couldn\'t parse float: ' + tok;
+    return val * sign;
+  };
+}
+
+/**
+ * A boolean parser.
+ * @returns A cmd token transformer.
+ */
+export function boolType()
+{
+  return (ctx: ParseContext): boolean => {
+    let tok = ctx.consumeToken();
+    const idx = ['false', 'true'].indexOf(tok);
+
+    if (idx == -1)
+      throw 'invalid boolean: ' + tok;
+    return !!idx;
+  };
+}
+
+/**
+ * An integer parser.
+ * @returns A cmd token transformer.
+ */
+export function intType()
+{
+  return (ctx: ParseContext): number => {
+    const tok = ctx.consumeToken();
+    const val = parseInt(tok);
+
+    if (isNaN(val))
+      throw 'invalid integer: ' + tok;
+    return val;
+  };
+}
+
+/**
+ * A rest argument parser.
+ * @param parser The parser to transform values.
+ * @returns A cmd token transformer.
+ */
+export function restType<T>(parser: Transformer<T>)
+{
+  return (ctx: ParseContext): T[] => {
+    const vals: T[] = [];
+
+    while (!ctx.isEndOfTokens)
+      vals.push(parser(ctx));
+    return vals;
+  };
+}
+
+/**
+ * An enumeration parser.
+ * @param opts The enum options.
+ * @returns The selected value.
+ */
+export function enumType(...opts: string[])
+{
+  return (ctx: ParseContext): any => {
+    const tok = ctx.consumeToken();
+
+    if (opts.includes(tok))
+      throw 'unknown enum option: ' + tok + '\n' +
+            'expected one of: ' + opts.join(', ');
+
+    return tok;
+  };
+}