[add] example:arithmetics

examples/arithmetics/arithmetic.tp2.json

@@ -0,0 +1,101 @@
+{
+	"version": "2",
+	"lexer_rules": [
+		{
+			"pattern": " |\\t|\\n",
+			"pass": false,
+			"name": null
+		},
+		{
+			"pattern": "[0-9]+",
+			"pass": true,
+			"name": "[const]"
+		},
+		{
+			"pattern": "\\+",
+			"pass": false,
+			"name": "[plus]"
+		},
+		{
+			"pattern": "-",
+			"pass": false,
+			"name": "[minus]"
+		},
+		{
+			"pattern": "\\*",
+			"pass": false,
+			"name": "[times]"
+		},
+		{
+			"pattern": "/",
+			"pass": false,
+			"name": "[divided]"
+		},
+		{
+			"pattern": "\\(",
+			"pass": false,
+			"name": "[open]"
+		},
+		{
+			"pattern": "\\)|",
+			"pass": false,
+			"name": "[close]"
+		}
+	],
+	"parser_rules": [
+		{
+			"label": "{constant}",
+			"premise": "<expression>",
+			"conclusion": [
+				{"type": "terminal", "parameters": {"id": "[const]"}}
+			]
+		},
+		{
+			"label": "{product}",
+			"premise": "<expression>",
+			"conclusion": [
+				{"type": "variable", "parameters": {"id": "<expression>"}},
+				{"type": "terminal", "parameters": {"id": "[times]"}},
+				{"type": "variable", "parameters": {"id": "<expression>"}}
+			]
+		},
+		{
+			"label": "{quotient}",
+			"premise": "<expression>",
+			"conclusion": [
+				{"type": "variable", "parameters": {"id": "<expression>"}},
+				{"type": "terminal", "parameters": {"id": "[divided]"}},
+				{"type": "variable", "parameters": {"id": "<expression>"}}
+			]
+		},
+		{
+			"label": "{sum}",
+			"premise": "<expression>",
+			"conclusion": [
+				{"type": "variable", "parameters": {"id": "<expression>"}},
+				{"type": "terminal", "parameters": {"id": "[plus]"}},
+				{"type": "variable", "parameters": {"id": "<expression>"}}
+			]
+		},
+		{
+			"label": "{difference}",
+			"premise": "<expression>",
+			"conclusion": [
+				{"type": "variable", "parameters": {"id": "<expression>"}},
+				{"type": "terminal", "parameters": {"id": "[minus]"}},
+				{"type": "variable", "parameters": {"id": "<expression>"}}
+			]
+		},
+		{
+			"label": "{priorised}",
+			"premise": "<expression>",
+			"conclusion": [
+				{"type": "terminal", "parameters": {"id": "[open]"}},
+				{"type": "variable", "parameters": {"id": "<expression>"}},
+				{"type": "terminal", "parameters": {"id": "[close]"}}
+			]
+		}
+	],
+	"parser_start": "<expression>"
+}
+

examples/arithmetics/eval

@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+
+import sys as _sys
+import json as _json
+
+
+def evaluate(node):
+	# _sys.stderr.write("eval: %s\n" % _json.dumps(node))
+	if (node["label"] == "{constant}"):
+		return int(node["value"][0]["data"]["value"])
+	elif (node["label"] == "{sum}"):
+		return (evaluate(node["children"][0]) + evaluate(node["children"][1]))
+	elif (node["label"] == "{difference}"):
+		return (evaluate(node["children"][0]) - evaluate(node["children"][1]))
+	elif (node["label"] == "{product}"):
+		return (evaluate(node["children"][0]) * evaluate(node["children"][1]))
+	elif (node["label"] == "{quotient}"):
+		return (evaluate(node["children"][0]) / evaluate(node["children"][1]))
+	elif (node["label"] == "{priorised}"):
+		return evaluate(node["children"][0])
+	else:
+		raise ValueError("unhandled label: " + node["label"])
+	
+
+def main():
+	content = _sys.stdin.read()
+	node = _json.loads(content)
+	value = evaluate(node)
+	_sys.stdout.write(str(value) + "\n")
+	
+
+main()
+