feat: Enhance template rendering and function library with new features and improvements

Author: hind-sagar-biswas

examples/initial.jhp

@@ -1,30 +1,30 @@
 {% include 'header.jhp' %}
 
-<h2>Hello {{ user.name }}! </h2>
+<h2>Hello {{ touppercase(user.gender) }} - {{ user.name }}! </h2>
 <p>
-{% if (user.age >= 100) %}
-  Damn! You're still kickin, huh?
-  You are a really strong 
-  {% if (user.gender == "M") %}
-    Man
+  {% if (user.age >= 100) %}
+    Damn! You're still kickin, huh?
+    You are a really strong 
+    {% if (user.gender == "m") %}
+      Man
+    {% else %}
+      Woman
+    {% endif %}
+    if I must say....!
+  {% elseif (user.age >= 10 + 8) %}
+    Adult? {{ 3 + 27  * 7 / (1 + 4) }}
   {% else %}
-    Woman
+    Minor
   {% endif %}
-  if I must say....!
-{% elseif (user.age >= 10 + 8) %}
-  Adult? {{ 3 + 27  * 7 / (1 + 4) }}
-{% else %}
-  Minor
-{% endif %}
 </p>
 <ul>
-{% for (i = 0; i < 10; i++) %}
-  <li>{{ i + 1 }}. Item no. {{ i }}! 
-{% endfor %}
+  {% for (i = 0; i < 10; i++) %}
+    <li>{{ i + 1 }}. Item no. {{ i }}! 
+  {% endfor %}
 </ul>
 <p>
-Escaped: {{ '<b>bold</b>' }}
-Raw: {{{ '<b>bold</b>' }}}
+  Escaped: {{ '<b>bold</b>' }}
+  Raw: {{{ '<b>bold</b>' }}}
 </p>
 
 {% include 'footer.jhp' %}

src/main/java/com/hindbiswas/jhp/App.java

@@ -7,6 +7,9 @@
 import com.hindbiswas.jhp.ast.AstPrettyPrinter;
 import com.hindbiswas.jhp.ast.AstRendererOld;
 import com.hindbiswas.jhp.ast.TemplateNode;
+import com.hindbiswas.jhp.engine.FunctionLibrary;
+import com.hindbiswas.jhp.engine.JhpEngine;
+import com.hindbiswas.jhp.engine.Settings;
 
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -16,7 +19,26 @@
 
 public class App {
     public static void main(String[] args) throws Exception {
-        ParseTree tree = generateTree("/home/shinigami/Java/java-hypertext-preprocessor/examples/initial.jhp");
+        String file = "/home/shinigami/Java/java-hypertext-preprocessor/examples/initial.jhp";
+
+        Settings settings = Settings.builder().base("/home/shinigami/Java/java-hypertext-preprocessor/examples/").build();
+        FunctionLibrary lib = new FunctionLibrary();
+        JhpEngine engine = new JhpEngine(settings, lib);
+
+        Map<String, Object> ctx = new HashMap<>();
+        Map<String, Object> user = new HashMap<>();
+        user.put("name", "Alice");
+        user.put("age", 150);
+        user.put("gender", "f");
+        ctx.put("user", user);
+        ctx.put("title", "Test JHP");
+
+        String out = engine.render(file, ctx);
+        System.out.println(out);
+    }
+
+    public static void oldReneder(String file) throws Exception {
+        ParseTree tree = generateTree(file);
         AstBuilder builder = new AstBuilder();
         TemplateNode ast = (TemplateNode) builder.visit(tree);
         AstPrettyPrinter.print(ast);
@@ -34,7 +56,6 @@ public static void main(String[] args) throws Exception {
         AstRendererOld renderer = new AstRendererOld(Path.of("examples")); // optional base dir
         String out = renderer.render(ast, ctx);
         System.out.println(out);
-
     }
 
     public static ParseTree generateTree(String file) throws Exception {

src/main/java/com/hindbiswas/jhp/ast/AstRenderer.java

@@ -5,7 +5,7 @@
 import java.nio.file.Path;
 import java.util.*;
 
-import com.hindbiswas.jhp.engine.FunctionLibrary;
+import com.hindbiswas.jhp.engine.FunctionLibraryContext;
 import com.hindbiswas.jhp.engine.IssueType;
 import com.hindbiswas.jhp.engine.PathResolver;
 import com.hindbiswas.jhp.engine.PathToAstParser;
@@ -18,13 +18,13 @@ public class AstRenderer {
     private final Settings settings;
     private final PathToAstParser parser;
     private final PathResolver pathResolver;
-    private final FunctionLibrary functions;
+    private final FunctionLibraryContext functions;
     private final RuntimeIssueResolver issueResolver;
 
     // per-thread include stack for cycle detection
     private final ThreadLocal<Deque<Path>> includeStack = ThreadLocal.withInitial(ArrayDeque::new);
 
-    public AstRenderer(Settings settings, FunctionLibrary functions, RuntimeIssueResolver issueResolver,
+    public AstRenderer(Settings settings, FunctionLibraryContext functions, RuntimeIssueResolver issueResolver,
             PathResolver pathResolver, PathToAstParser parser) {
         this.settings = settings;
         this.functions = functions;
@@ -104,13 +104,15 @@ private void renderInclude(IncludeNode node, Deque<Map<String, Object>> scopes,
             issueResolver.handle(IssueType.MISSING_INCLUDE, e.getMessage(), sb, includeStack);
             return;
         } catch (Exception e) {
-            issueResolver.handle(IssueType.INCLUDE_ERROR, "Something went wrong trying to resolve the include path: " + node.path + ".", sb, includeStack);
+            issueResolver.handle(IssueType.INCLUDE_ERROR,
+                    "Something went wrong trying to resolve the include path: " + node.path + ".", sb, includeStack);
             return;
         }
 
         // Check max depth
         if (stack.size() >= settings.maxIncludeDepth) {
-            issueResolver.handle(IssueType.INCLUDE_MAX_DEPTH, "Max include depth reached: " + settings.maxIncludeDepth, sb, includeStack);
+            issueResolver.handle(IssueType.INCLUDE_MAX_DEPTH, "Max include depth reached: " + settings.maxIncludeDepth,
+                    sb, includeStack);
             return;
         }
 
@@ -138,7 +140,8 @@ private void renderInclude(IncludeNode node, Deque<Map<String, Object>> scopes,
             }
 
         } catch (Exception ex) {
-            issueResolver.handle(IssueType.INCLUDE_ERROR, "Something went wrong trying to parse the include: " + node.path + ".", sb, includeStack);
+            issueResolver.handle(IssueType.INCLUDE_ERROR,
+                    "Something went wrong trying to parse the include: " + node.path + ".", sb, includeStack);
         }
     }
 
@@ -320,12 +323,41 @@ private Object evalExpression(ExpressionNode expr, Deque<Map<String, Object>> sc
         }
         if (expr instanceof FunctionCallNode) {
             FunctionCallNode f = (FunctionCallNode) expr;
-            Object callee = evalExpression(f.callee, scopes);
+
+            // Determine function name (prefer raw identifier names)
+            String fnName = null;
+            if (f.callee instanceof IdentifierNode id) {
+                fnName = id.name; // function name literal
+            } else {
+                Object calleeVal = evalExpression(f.callee, scopes);
+                if (calleeVal instanceof String)
+                    fnName = (String) calleeVal;
+            }
+
+            // build args
             List<Object> args = new ArrayList<>();
             for (ExpressionNode e : f.args)
                 args.add(evalExpression(e, scopes));
-            return callFunction(callee, args, scopes);
+
+            if (fnName != null) {
+                try {
+                    return functions.callFunction(fnName, args, scopes);
+                } catch (Exception ex) {
+                    StringBuilder tmp = new StringBuilder();
+                    issueResolver.handle(IssueType.FUNCTION_ERROR,
+                            "Function '" + fnName + "' threw: " + ex.getClass().getSimpleName() + ": "
+                                    + ex.getMessage(),
+                            tmp, includeStack);
+                    return tmp.toString();
+                }
+            } else {
+                StringBuilder tmp = new StringBuilder();
+                issueResolver.handle(IssueType.FUNCTION_CALL_ERROR,
+                        "Invalid function call: " + String.valueOf(f.callee), tmp, includeStack);
+                return tmp.toString();
+            }
         }
+
         if (expr instanceof UnaryOpNode) {
             UnaryOpNode u = (UnaryOpNode) expr;
             Object v = evalExpression(u.expr, scopes);

src/main/java/com/hindbiswas/jhp/engine/FunctionLibrary.java

@@ -1,9 +1,119 @@
 package com.hindbiswas.jhp.engine;
 
-import java.util.List;
-import java.util.Deque;
-import java.util.Map;
+import java.time.Instant;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 
-public interface FunctionLibrary {
-    Object callFunction(String name, List<Object> args, Deque<Map<String, Object>> scopes);
+public class FunctionLibrary implements FunctionLibraryContext {
+
+    @FunctionalInterface
+    public interface JhpFunction {
+        Object apply(List<Object> args, Deque<Map<String, Object>> scopes);
+    }
+
+    private final Map<String, JhpFunction> stdLib;
+    private final Map<String, JhpFunction> userLib; 
+
+    public FunctionLibrary() {
+        this.userLib = new ConcurrentHashMap<>();
+        Map<String, JhpFunction> builtins = new HashMap<>();
+
+        // now() -> returns Instant.now()
+        builtins.put("now", (args, scopes) -> {
+            if (args != null && !args.isEmpty()) {
+                // ignore args but be forgiving
+            }
+            return Instant.now();
+        });
+
+        // toUppercase(s)
+        builtins.put("touppercase", (args, scopes) -> {
+            if (args == null || args.isEmpty() || args.get(0) == null) return null;
+            return args.get(0).toString().toUpperCase();
+        });
+
+        // toLowerCase(s)
+        builtins.put("tolowercase", (args, scopes) -> {
+            if (args == null || args.isEmpty() || args.get(0) == null) return null;
+            return args.get(0).toString().toLowerCase();
+        });
+
+        // trim(s)
+        builtins.put("trim", (args, scopes) -> {
+            if (args == null || args.isEmpty() || args.get(0) == null) return null;
+            return args.get(0).toString().trim();
+        });
+
+        // Example: len(s|collection|map)
+        builtins.put("len", (args, scopes) -> {
+            if (args == null || args.isEmpty() || args.get(0) == null) return 0;
+            Object o = args.get(0);
+            if (o instanceof CharSequence) return ((CharSequence) o).length();
+            if (o instanceof Collection) return ((Collection<?>) o).size();
+            if (o instanceof Map) return ((Map<?, ?>) o).size();
+            if (o.getClass().isArray()) return java.lang.reflect.Array.getLength(o);
+            return 0;
+        });
+
+        this.stdLib = Collections.unmodifiableMap(builtins);
+    }
+
+    public JhpFunction register(String name, JhpFunction fn) throws IllegalArgumentException {
+        validateNameAndFn(name, fn);
+        return userLib.put(normalize(name), fn);
+    }
+
+    public JhpFunction unregister(String name) {
+        if (name == null) return null;
+        return userLib.remove(normalize(name));
+    }
+
+    public boolean hasFunction(String name) {
+        if (name == null) return false;
+        String n = normalize(name);
+        return userLib.containsKey(n) || stdLib.containsKey(n);
+    }
+
+    @Override
+    public Object callFunction(String name, List<Object> args, Deque<Map<String, Object>> scopes) {
+        if (name == null) throw new IllegalArgumentException("Function name cannot be null");
+        String n = normalize(name);
+
+        // priority: userLib -> stdLib
+        JhpFunction fn = userLib.get(n);
+        if (fn != null) {
+            return safeInvoke(fn, args, scopes, n);
+        }
+
+        fn = stdLib.get(n);
+        if (fn != null) {
+            return safeInvoke(fn, args, scopes, n);
+        }
+
+        throw new IllegalArgumentException("Function not found: " + name);
+    }
+
+    /* ----------------- helpers ----------------- */
+
+    private Object safeInvoke(JhpFunction fn, List<Object> args, Deque<Map<String, Object>> scopes, String name) {
+        try {
+            return fn.apply(args == null ? Collections.emptyList() : args, scopes);
+        } catch (RuntimeException re) {
+            // wrap to provide contextual info
+            throw new RuntimeException("Error executing function '" + name + "': " + re.getMessage(), re);
+        }
+    }
+
+    private void validateNameAndFn(String name, JhpFunction fn) throws IllegalArgumentException {
+        if (name == null || name.trim().isEmpty()) {
+            throw new IllegalArgumentException("Function name cannot be null/empty");
+        }
+        if (fn == null) {
+            throw new IllegalArgumentException("Function implementation cannot be null");
+        }
+    }
+
+    private String normalize(String name) {
+        return name.trim().toLowerCase(Locale.ROOT);
+    }
 }

src/main/java/com/hindbiswas/jhp/engine/FunctionLibraryContext.java

@@ -0,0 +1,9 @@
+package com.hindbiswas.jhp.engine;
+
+import java.util.List;
+import java.util.Deque;
+import java.util.Map;
+
+public interface FunctionLibraryContext {
+    Object callFunction(String name, List<Object> args, Deque<Map<String, Object>> scopes);
+}

src/main/java/com/hindbiswas/jhp/engine/JhpEngine.java

@@ -97,9 +97,12 @@ private final class IssueResolver implements RuntimeIssueResolver {
         public void handle(IssueType type, String message, StringBuilder sb, ThreadLocal<Deque<Path>> includeStack) {
             if (settings.issueHandleMode == IssueHandleMode.COMMENT) {
                 sb.append("<!-- ").append(type).append(": ").append(message).append(" -->\n");
-            } else if (settings.issueHandleMode == IssueHandleMode.THROW) {
+                return;
+            }
+            if (settings.issueHandleMode == IssueHandleMode.THROW) {
                 throw new RuntimeException(type + ": " + message);
-            } else if (settings.issueHandleMode == IssueHandleMode.DEBUG) {
+            }
+            if (settings.issueHandleMode == IssueHandleMode.DEBUG) {
                 // Build debug info
                 String ts = java.time.Instant.now().toString();
                 String thread = Thread.currentThread().getName();
@@ -166,9 +169,8 @@ public void handle(IssueType type, String message, StringBuilder sb, ThreadLocal
                 sb.append("</details>\n");
 
                 sb.append("<!-- ISSUE DEBUG END -->\n");
-            } else if (settings.issueHandleMode == IssueHandleMode.IGNORE) {
-                // intentionally do nothing
-            }
+            } 
+            
         }
 
         // small helper to append a table row (keeps HTML escaped where appropriate)
@@ -205,21 +207,26 @@ private String escapeHtml(String s) {
 
     private final AstParser parser = new AstParser();
     private final Settings settings;
-    private final FunctionLibrary functionLibrary;
+    private final FunctionLibraryContext functionLibrary;
     private final RuntimeIssueResolver issueResolver = new IssueResolver();
+    private final IncludePathResolver includePathResolver = new IncludePathResolver();
 
     // AST cache
     private final Map<Path, TemplateNode> astCache = new HashMap<>();
 
-    public JhpEngine(Settings settings, FunctionLibrary functionLibrary) {
+    public JhpEngine(Settings settings, FunctionLibraryContext functionLibrary) {
         this.settings = settings;
         this.functionLibrary = functionLibrary;
     }
 
     public String render(Path templatePath, Map<String, Object> context) throws Exception {
         TemplateNode ast = parser.parse(templatePath);
-        AstRenderer renderer = new AstRenderer(settings, functionLibrary, issueResolver, new IncludePathResolver(),
-                parser);
+        AstRenderer renderer = new AstRenderer(settings, functionLibrary, issueResolver, includePathResolver, parser);
         return renderer.render(ast, context);
     }
+
+    public String render(String pathTxt, Map<String, Object> context) throws Exception {
+        Path path = includePathResolver.resolve(pathTxt, null);
+        return render(path, context);
+    }
 }

src/main/java/com/hindbiswas/jhp/engine/Settings.java

@@ -9,8 +9,8 @@ public static final class SettingsBuilder {
         private int maxIncludeDepth = defaultMaxIncludeDepth;
         private IssueHandleMode issueHandleMode = defaultIssueHandleMode;
 
-        public SettingsBuilder base(Path base) {
-            this.base = base;
+        public SettingsBuilder base(String base) {
+            this.base = Path.of(base);
             return this;
         }