Script if expression support (#575)

* script: Rename select intrinsic * script: Lex if keyword * script: Lex else keyword * script: If expression support
BastianBlokland · Sep 8, 2023 · 38df4fa · 38df4fa
1 parent a0640b7
commit 38df4fa
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Showing 12 changed files with 116 additions and 23 deletions.
diff --git a/apps/utilities/repl.c b/apps/utilities/repl.c
@@ -65,6 +65,9 @@ static TtyFgColor repl_token_color(const ScriptTokenType tokenType) {
   case ScriptTokenType_QMarkQMark:
   case ScriptTokenType_QMarkQMarkEq:
     return TtyFgColor_Green;
+  case ScriptTokenType_If:
+  case ScriptTokenType_Else:
+    return TtyFgColor_Cyan;
   case ScriptTokenType_ParenOpen:
   case ScriptTokenType_ParenClose:
   case ScriptTokenType_CurlyOpen:

diff --git a/libs/script/include/script_error.h b/libs/script/include/script_error.h
@@ -15,6 +15,7 @@ typedef enum {
   ScriptError_UnterminatedArgumentList,
   ScriptError_BlockSizeExceedsMaximum,
   ScriptError_ArgumentCountExceedsMaximum,
+  ScriptError_InvalidConditionCountForIf,
   ScriptError_MissingColonInSelectExpression,
   ScriptError_UnexpectedTokenAfterExpression,
 

diff --git a/libs/script/include/script_intrinsic.h b/libs/script/include/script_intrinsic.h
@@ -31,7 +31,7 @@ typedef enum {
   ScriptIntrinsic_Angle,
   ScriptIntrinsic_RandomBetween,
   ScriptIntrinsic_ComposeVector3,
-  ScriptIntrinsic_Select,
+  ScriptIntrinsic_If,
 
   ScriptIntrinsic_Count,
 } ScriptIntrinsic;

diff --git a/libs/script/include/script_lex.h b/libs/script/include/script_lex.h
@@ -36,6 +36,8 @@ typedef enum {
   ScriptTokenType_Number,       // 42.1337
   ScriptTokenType_Identifier,   // foo
   ScriptTokenType_Key,          // $bar
+  ScriptTokenType_If,           // if
+  ScriptTokenType_Else,         // else
   ScriptTokenType_Error,        //
   ScriptTokenType_End,          // \0
 } ScriptTokenType;

diff --git a/libs/script/src/error.c b/libs/script/src/error.c
@@ -16,6 +16,7 @@ static const String g_errorStrs[] = {
     string_static("UnterminatedArgumentList"),
     string_static("BlockSizeExceedsMaximum"),
     string_static("ArgumentCountExceedsMaximum"),
+    string_static("InvalidConditionCountForIf"),
     string_static("MissingColonInSelectExpression"),
     string_static("UnexpectedTokenAfterExpression"),
 };

diff --git a/libs/script/src/eval.c b/libs/script/src/eval.c
@@ -98,10 +98,8 @@ INLINE_HINT static ScriptVal eval_intr(ScriptEvalContext* ctx, const ScriptExprI
     return script_val_random_between(eval(ctx, args[0]), eval(ctx, args[1]));
   case ScriptIntrinsic_ComposeVector3:
     return script_val_compose_vector3(eval(ctx, args[0]), eval(ctx, args[1]), eval(ctx, args[2]));
-  case ScriptIntrinsic_Select: {
-    const ScriptVal condition = eval(ctx, args[0]);
-    return script_truthy(condition) ? eval(ctx, args[1]) : eval(ctx, args[2]);
-  }
+  case ScriptIntrinsic_If:
+    return script_truthy(eval(ctx, args[0])) ? eval(ctx, args[1]) : eval(ctx, args[2]);
   case ScriptIntrinsic_Count:
     break;
   }

diff --git a/libs/script/src/intrinsic.c b/libs/script/src/intrinsic.c
@@ -36,7 +36,7 @@ u32 script_intrinsic_arg_count(const ScriptIntrinsic i) {
   case ScriptIntrinsic_RandomBetween:
     return 2;
   case ScriptIntrinsic_ComposeVector3:
-  case ScriptIntrinsic_Select:
+  case ScriptIntrinsic_If:
     return 3;
   case ScriptIntrinsic_Count:
     break;
@@ -77,7 +77,7 @@ String script_intrinsic_str(const ScriptIntrinsic i) {
       string_static("angle"),
       string_static("random-between"),
       string_static("compose-vector3"),
-      string_static("select"),
+      string_static("if"),
   };
   ASSERT(array_elems(g_names) == ScriptIntrinsic_Count, "Incorrect number of names");
   return g_names[i];

diff --git a/libs/script/src/lex.c b/libs/script/src/lex.c
@@ -109,6 +109,13 @@ static String script_lex_identifier(String str, ScriptToken* out) {
     return str;
   }
 
+  if (string_eq(identifier, string_lit("if"))) {
+    return out->type = ScriptTokenType_If, string_consume(str, end);
+  }
+  if (string_eq(identifier, string_lit("else"))) {
+    return out->type = ScriptTokenType_Else, string_consume(str, end);
+  }
+
   out->type           = ScriptTokenType_Identifier;
   out->val_identifier = string_hash(identifier);
   return string_consume(str, end);
@@ -313,6 +320,10 @@ String script_token_str_scratch(const ScriptToken* token) {
     return fmt_write_scratch("${}", fmt_int(token->val_identifier, .base = 16));
   case ScriptTokenType_Key:
     return fmt_write_scratch("${}", fmt_int(token->val_key, .base = 16));
+  case ScriptTokenType_If:
+    return string_lit("if");
+  case ScriptTokenType_Else:
+    return string_lit("else");
   case ScriptTokenType_Error:
     return script_error_str(token->val_error);
   case ScriptTokenType_End:

diff --git a/libs/script/src/read.c b/libs/script/src/read.c
@@ -296,7 +296,7 @@ static ScriptReadResult read_expr_constant(ScriptReadContext* ctx, const StringH
 static ScriptReadResult read_expr_function(ScriptReadContext* ctx, const StringHash identifier) {
   ScriptExpr             args[script_args_max];
   const ScriptArgsResult argsRes = read_args(ctx, args);
-  if (argsRes.type == ScriptResult_Fail) {
+  if (UNLIKELY(argsRes.type == ScriptResult_Fail)) {
     return script_err(argsRes.error);
   }
 
@@ -312,6 +312,45 @@ static ScriptReadResult read_expr_function(ScriptReadContext* ctx, const StringH
   return script_err(ScriptError_NoFunctionFoundForIdentifier);
 }
 
+static ScriptReadResult read_expr_if(ScriptReadContext* ctx) {
+  ScriptToken token;
+  ctx->input = script_lex(ctx->input, g_stringtable, &token);
+  if (UNLIKELY(token.type != ScriptTokenType_ParenOpen)) {
+    return script_err(ScriptError_InvalidConditionCountForIf);
+  }
+
+  ScriptExpr             conditions[script_args_max];
+  const ScriptArgsResult conditionRes = read_args(ctx, conditions);
+  if (UNLIKELY(conditionRes.type == ScriptResult_Fail)) {
+    return script_err(conditionRes.error);
+  }
+  if (UNLIKELY(conditionRes.argCount != 1)) {
+    return script_err(ScriptError_InvalidConditionCountForIf);
+  }
+
+  const ScriptReadResult b1 = read_expr(ctx, OpPrecedence_None);
+  if (UNLIKELY(b1.type == ScriptResult_Fail)) {
+    return b1;
+  }
+
+  ScriptExpr   b2Expr;
+  const String remInput = script_lex(ctx->input, null, &token);
+  if (token.type == ScriptTokenType_Else) {
+    ctx->input = remInput; // Consume the else keyword.
+
+    const ScriptReadResult b2 = read_expr(ctx, OpPrecedence_None);
+    if (UNLIKELY(b2.type == ScriptResult_Fail)) {
+      return b2;
+    }
+    b2Expr = b2.expr;
+  } else {
+    b2Expr = script_add_value(ctx->doc, script_null());
+  }
+
+  const ScriptExpr intrArgs[] = {conditions[0], b1.expr, b2Expr};
+  return script_expr(script_add_intrinsic(ctx->doc, ScriptIntrinsic_If, intrArgs));
+}
+
 static ScriptReadResult read_expr_select(ScriptReadContext* ctx, const ScriptExpr condition) {
   const ScriptReadResult b1 = read_expr(ctx, OpPrecedence_None);
   if (UNLIKELY(b1.type == ScriptResult_Fail)) {
@@ -329,29 +368,33 @@ static ScriptReadResult read_expr_select(ScriptReadContext* ctx, const ScriptExp
     return b2;
   }
 
-  const ScriptIntrinsic intr       = ScriptIntrinsic_Select;
-  const ScriptExpr      intrArgs[] = {condition, b1.expr, b2.expr};
-  return script_expr(script_add_intrinsic(ctx->doc, intr, intrArgs));
+  const ScriptExpr intrArgs[] = {condition, b1.expr, b2.expr};
+  return script_expr(script_add_intrinsic(ctx->doc, ScriptIntrinsic_If, intrArgs));
 }
 
 static ScriptReadResult read_expr_primary(ScriptReadContext* ctx) {
   ScriptToken token;
   ctx->input = script_lex(ctx->input, g_stringtable, &token);
 
   switch (token.type) {
-    /**
-     * Parenthesized expression.
-     */
+  /**
+   * Parenthesized expression.
+   */
   case ScriptTokenType_ParenOpen:
     return read_expr_paren(ctx);
-    /**
-     * Scope.
-     */
+  /**
+   * Scope.
+   */
   case ScriptTokenType_CurlyOpen:
     return read_expr_block(ctx, ScriptBlockType_Scope);
-    /**
-     * Identifiers.
-     */
+  /**
+   * Keywords.
+   */
+  case ScriptTokenType_If:
+    return read_expr_if(ctx);
+  /**
+   * Identifiers.
+   */
   case ScriptTokenType_Identifier: {
     ScriptToken  nextToken;
     const String remInput = script_lex(ctx->input, null, &nextToken);

diff --git a/libs/script/test/test_lex.c b/libs/script/test/test_lex.c
@@ -101,6 +101,9 @@ spec(lex) {
         {string_static(" \t $héllo"), tok_key_lit("héllo")},
         {string_static("$"), tok_err(KeyEmpty)},
 
+        {string_static("if"), tok_simple(If)},
+        {string_static("else"), tok_simple(Else)},
+
         {string_static("&"), tok_err(InvalidChar)},
         {string_static("|"), tok_err(InvalidChar)},
         {string_static("@"), tok_err(InvalidChar)},

diff --git a/libs/script/test/test_read.c b/libs/script/test/test_read.c
@@ -94,6 +94,32 @@ spec(read) {
         {string_static("((42.1337))"), string_static("[value: 42.1337]")},
         {string_static("(($hello))"), string_static("[mem-load: $3944927369]")},
 
+        // If expressions.
+        {
+            string_static("if(true) 2"),
+            string_static("[intrinsic: if]\n"
+                          "  [value: true]\n"
+                          "  [value: 2]\n"
+                          "  [value: null]"),
+        },
+        {
+            string_static("if(true) 2 else 3"),
+            string_static("[intrinsic: if]\n"
+                          "  [value: true]\n"
+                          "  [value: 2]\n"
+                          "  [value: 3]"),
+        },
+        {
+            string_static("if(false) 2 else if(true) 3"),
+            string_static("[intrinsic: if]\n"
+                          "  [value: false]\n"
+                          "  [value: 2]\n"
+                          "  [intrinsic: if]\n"
+                          "    [value: true]\n"
+                          "    [value: 3]\n"
+                          "    [value: null]"),
+        },
+
         // Unary expressions.
         {
             string_static("-42"),
@@ -201,14 +227,14 @@ spec(read) {
         // Ternary expressions.
         {
             string_static("true ? 1 : 2"),
-            string_static("[intrinsic: select]\n"
+            string_static("[intrinsic: if]\n"
                           "  [value: true]\n"
                           "  [value: 1]\n"
                           "  [value: 2]"),
         },
         {
             string_static("1 > 2 ? 1 + 2 : 3 + 4"),
-            string_static("[intrinsic: select]\n"
+            string_static("[intrinsic: if]\n"
                           "  [intrinsic: greater]\n"
                           "    [value: 1]\n"
                           "    [value: 2]\n"
@@ -478,6 +504,12 @@ spec(read) {
         {string_static("{1;"), ScriptError_UnterminatedScope},
         {string_static("{1;2"), ScriptError_UnterminatedScope},
         {string_static("{1;2;"), ScriptError_UnterminatedScope},
+        {string_static("if"), ScriptError_InvalidConditionCountForIf},
+        {string_static("if("), ScriptError_UnterminatedArgumentList},
+        {string_static("if()"), ScriptError_InvalidConditionCountForIf},
+        {string_static("if(1,2)"), ScriptError_InvalidConditionCountForIf},
+        {string_static("if(1)"), ScriptError_MissingPrimaryExpression},
+        {string_static("if(1) 1 else"), ScriptError_MissingPrimaryExpression},
     };
 
     for (u32 i = 0; i != array_elems(g_testData); ++i) {

diff --git a/libs/script/test/utils_internal.h b/libs/script/test/utils_internal.h
@@ -6,7 +6,6 @@
 // clang-format off
 
 #define tok_simple(_TYPE_) (ScriptToken){.type = ScriptTokenType_##_TYPE_}
-#define tok_null(void)     (ScriptToken){.type = ScriptTokenType_Null}
 #define tok_number(_VAL_)  (ScriptToken){.type = ScriptTokenType_Number, .val_number = (_VAL_)}
 #define tok_bool(_VAL_)    (ScriptToken){.type = ScriptTokenType_Bool, .val_bool = (_VAL_)}
 #define tok_id(_VAL_)      (ScriptToken){.type = ScriptTokenType_Identifier, .val_identifier = string_hash(_VAL_)}