expression parser; first pass.

2026-08-04 14:48:44 +00:00 · 2021-09-07 18:16:57 +02:00
parent c0a56dbcda
commit c6c790e50d
10 changed files with 478 additions and 13 deletions
@@ -0,0 +1,254 @@
+//$ exe //
+
+#if 0
+#define ASSERT(expr) {if(!(expr)){fprintf(stderr, "Assertion failed: %s, line %d (%s)\n", __FILE__, __LINE__, #expr); __builtin_debugtrap();}}
+#define HARD_ASSERT(expr) {if(!(expr)){fprintf(stderr, "Assertion failed: %s, line %d (%s)\n", __FILE__, __LINE__, #expr); __builtin_debugtrap();}}
+#define BP ASSERT(!"Break point");
+#define NotTested ASSERT(!"Not tested");
+#define STATIC_ASSERT(expr) U8 MACRO_CONCAT(static_assert_, __COUNTER__)[(expr)?(1):(-1)]
+#define NotImplemented ASSERT(!"Not implemented");
+#endif
+
+
+#include "md.h"
+#include "md.c"
+
+MD_Arena *arena = 0;
+
+typedef struct Expression_QA Expression_QA;
+struct Expression_QA
+{
+    char *q;
+    char *a;
+};
+
+typedef struct OperatorDescription OperatorDescription;
+struct OperatorDescription{
+    MD_String8 s;
+    MD_ExprOperator op;
+};
+
+// NOTE(mal): Based on https://en.wikipedia.org/wiki/Operators_in_C_and_C%2B%2B#Operator_precedence 2021-09-05
+//            Precedences are flipped. The ones listed here are 20-x where x is the precedence on the wikipedia table
+#define OPERATORS \
+    X(PostFixIncrement,    "++",        Postfix,                18) \
+    X(PostFixDecrement,    "--",        Postfix,                18) \
+    X(Call,                "()",        Postfix,                18) \
+    X(ArraySubscript,      "[]",        Binary,                 18) \
+    X(Member,              ".",         Binary,                 18) \
+    X(PointerMember,       "->",        Binary,                 18) \
+    X(PreFixIncrement,     "++",        Prefix,                 17) \
+    X(PreFixDecrement,     "--",        Prefix,                 17) \
+    X(UnaryPlus,           "+",         Prefix,                 17) \
+    X(UnaryMinus,          "-",         Prefix,                 17) \
+    X(LogicalNot,          "!",         Prefix,                 17) \
+    X(BitwiseNot,          "~",         Prefix,                 17) \
+    X(Dereference,         "*",         Prefix,                 17) \
+    X(AddressOf,           "&",         Prefix,                 17) \
+    X(SizeOf,              "sizeof",    Prefix,                 17) /* NOTE(mal); Just for fun*/ \
+    X(Multiplication,      "*",         Binary,                 15) \
+    X(Division,            "/",         Binary,                 15) \
+    X(Modulo,              "%",         Binary,                 15) \
+    X(Addition,            "+",         Binary,                 14) \
+    X(Subtraction,         "-",         Binary,                 14) \
+    X(LeftShift,           "<<",        Binary,                 13) \
+    X(RightShift,          ">>",        Binary,                 13) \
+    X(LessThan,            "<",         Binary,                 11) \
+    X(LessThanOrEqual,     "<=",        Binary,                 11) \
+    X(GreaterThan,         ">",         Binary,                 11) \
+    X(GreaterThanOrEqual,  ">=",        Binary,                 11) \
+    X(Equal,               "==",        Binary,                 10) \
+    X(NotEqual,            "!=",        Binary,                 10) \
+    X(BitwiseAnd,          "&",         Binary,                  9) \
+    X(BitwiseXor,          "^",         Binary,                  8) \
+    X(BitwiseOr,           "|",         Binary,                  7) \
+    X(LogicalAnd,          "&&",        Binary,                  6) \
+    X(LogicalOr,           "||",        Binary,                  5) \
+    X(Assign,              "=",         BinaryRightAssociative,  4) \
+    X(AssignAddition,      "+=",        BinaryRightAssociative,  4) \
+    X(AssignSubtraction,   "-=",        BinaryRightAssociative,  4) \
+    X(AssignMultiplication,"*=",        BinaryRightAssociative,  4) \
+    X(AssignDivision,      "/=",        BinaryRightAssociative,  4) \
+    X(AssignModulo,        "%=",        BinaryRightAssociative,  4) \
+    X(AssignLeftShift,     "<<=",       BinaryRightAssociative,  4) \
+    X(AssignRightShift,    ">>=",       BinaryRightAssociative,  4) \
+    X(AssignBitwiseAnd,    "&=",        BinaryRightAssociative,  4) \
+    X(AssignBitwiseXor,    "^=",        BinaryRightAssociative,  4) \
+    X(AssignBitwiseOr,     "|=",        BinaryRightAssociative,  4)
+    // X(Cast                 "()",        Prefix,                 17)
+    // X(Comma,               ",",         Binary,                  3)
+
+#define X(name, token, kind, prec) Op_##name,
+typedef enum{
+    Op_Null,
+    OPERATORS
+    Op_COUNT
+} Op;
+#undef X
+
+
+static MD_String8 node_raw_contents(MD_Node *node, MD_b32 exclude_outer){
+    MD_String8 result = {0};
+
+    MD_u64 beg = node->offset;
+    if(exclude_outer && !MD_NodeIsNil(node->first_child)){
+        beg = node->first_child->offset;
+    }
+
+    MD_u64 end = beg; {
+        MD_Node *last_descendant = node;
+        while(!MD_NodeIsNil(last_descendant->last_child)){
+            last_descendant = last_descendant->last_child;
+        }
+        end = last_descendant->offset + last_descendant->raw_string.size;
+    }
+
+    MD_Node *root = node;
+    while(!MD_NodeIsNil(root->parent)){
+        root = root->parent;
+    }
+
+    result = MD_S8Substring(root->raw_string, beg, end);
+    return result;
+}
+
+static void parenthesize_exclude_outer(MD_Arena *arena, OperatorDescription *descs, MD_String8List *l, 
+                                       MD_ExprNode *node, MD_b32 exclude_outer_parens){
+    if(node->is_op){
+        if(!exclude_outer_parens){
+            MD_S8ListPush(arena, l, MD_S8Lit("("));
+        }
+
+        MD_ExprOperator *op = &descs[node->op_id].op;
+        if(op->kind == MD_ExprOperatorKind_Binary || op->kind == MD_ExprOperatorKind_BinaryRightAssociative){
+
+            parenthesize_exclude_outer(arena, descs, l, node->left, 0);
+
+            MD_b32 is_subscript = (node->op_id == Op_ArraySubscript);
+            if(is_subscript){
+                MD_S8ListPush(arena, l, MD_S8Lit("["));
+                parenthesize_exclude_outer(arena, descs, l, node->right, 1);
+                MD_S8ListPush(arena, l, MD_S8Lit("]"));
+            }
+            else{
+                MD_S8ListPush(arena, l, MD_S8Lit(" "));
+                MD_S8ListPush(arena, l, node->md_node->string);
+                MD_S8ListPush(arena, l, MD_S8Lit(" "));
+                parenthesize_exclude_outer(arena, descs, l, node->right, 0);
+            }
+        }
+        else if(op->kind == MD_ExprOperatorKind_Prefix){
+            MD_S8ListPush(arena, l, node->md_node->string);
+            MD_u8 last_op_c = MD_S8Suffix(node->md_node->string, 1).str[0];
+
+            if(MD_CharIsAlpha(last_op_c) || MD_CharIsDigit(last_op_c)){ // NOTE: Keyword prefix operator (e.g. sizeof)
+                MD_S8ListPush(arena, l, MD_S8Lit(" "));
+            }
+
+            parenthesize_exclude_outer(arena, descs, l, node->left, 0);
+        }
+        else if(op->kind == MD_ExprOperatorKind_Postfix){
+            parenthesize_exclude_outer(arena, descs, l, node->left, 0);
+
+            MD_b32 is_call = (node->op_id == Op_Call);
+            if(is_call){
+                MD_S8ListPush(arena, l, MD_S8Lit("(...)"));
+            }
+            else{
+                MD_S8ListPush(arena, l, node->md_node->string);
+            }
+        }
+        else{
+            MD_S8ListPush(arena, l, MD_S8Lit("--- Can't print expression ---"));
+        }
+
+        if(!exclude_outer_parens){
+            MD_S8ListPush(arena, l, MD_S8Lit(")"));
+        }
+    }
+    else{
+        if(MD_NodeIsNil(node->md_node->first_child)){
+            MD_S8ListPush(arena, l, node_raw_contents(node->md_node, 0));
+        }
+        else{
+            if(node->md_node->flags & MD_NodeFlag_HasBracketLeft && 
+               node->md_node->flags & MD_NodeFlag_HasBracketRight){
+                MD_S8ListPush(arena, l, MD_S8Lit("[...]"));
+            }
+            else if(node->md_node->flags & MD_NodeFlag_HasBraceLeft && 
+               node->md_node->flags & MD_NodeFlag_HasBraceRight){
+                MD_S8ListPush(arena, l, MD_S8Lit("{...}"));
+            }
+            else{
+                MD_S8ListPush(arena, l, MD_S8Lit("???"));
+            }
+        }
+    }
+}
+
+static MD_String8 parenthesize(MD_Arena *arena, OperatorDescription *descs, MD_ExprNode *node){
+    MD_String8 result = {0};
+    MD_String8List l = {0};
+    parenthesize_exclude_outer(arena, descs, &l, node, 1);
+    result = MD_S8ListJoin(arena, l, 0);
+    return result;
+}
+
+
+int main(void){
+    OperatorDescription operator_array[Op_COUNT] = {0};
+#define X(name, token, kind_, prec) \
+    operator_array[Op_##name].s = MD_S8Lit(token); \
+    operator_array[Op_##name].op = (MD_ExprOperator){ .op_id = Op_##name, .kind = MD_ExprOperatorKind_##kind_, .precedence = prec };
+    OPERATORS
+#undef X 
+
+    arena = MD_ArenaAlloc(1ull << 40);
+    MD_ExprOperatorList operator_list = {0};
+
+    for(Op op= Op_Null+1; op < Op_COUNT; ++op){
+        OperatorDescription *desc = operator_array + op;
+        MD_Node *node = MD_MakeNode(arena, MD_NodeKind_Main, desc->s, desc->s, 0);
+        MD_ExprOperatorPush(arena, &operator_list, op, desc->op.kind, desc->op.precedence, node);
+    }
+
+    MD_ExprOperatorTable op_table = MD_ExprBakeOperatorTableFromList(arena, &operator_list);
+
+    Expression_QA tests[] = {
+        { .q = "a + b + c",     .a = "(a + b) + c"      },
+        { .q = "a + (b + c)",   .a = "a + (b + c)"      },
+        { .q = "-a * b + c",    .a = "((-a) * b) + c"   },
+        { .q = "a * (b + c)",   .a = "a * (b + c)"      },
+        { .q = "a = b + c",     .a = "a = (b + c)"      },
+        { .q = "a(b,c)",        .a = "a(...)"           },
+        { .q = "(a + b)()",     .a = "(a + b)(...)"     },
+        { .q = "sizeof a + b",  .a = "(sizeof a) + b"   },
+        { .q = "[1, 100] * n",  .a = "[...] * n"        },
+        { .q = "a[b+c]",        .a = "a[b + c]"         },
+        { .q = "a++ + b",       .a = "(a++) + b"        },
+    };
+
+    for(MD_u32 i_test = 0; i_test < MD_ArrayCount(tests); i_test+=1){
+        Expression_QA test = tests[i_test];
+        MD_String8 q = MD_S8CString(test.q);
+        MD_String8 a = MD_S8CString(test.a);
+
+        MD_ParseResult parse = MD_ParseWholeString(arena, MD_S8Lit("test"), q);
+        MD_Assert(parse.errors.max_message_kind == MD_MessageKind_Null);
+        MD_ExprParseResult expr_parse = MD_ExprParse(arena, &op_table, parse.node->first_child, MD_NilNode());
+
+        if(expr_parse.errors.max_message_kind){
+            printf("Example %d : \"%.*s\". Got error \"%.*s\"\n", i_test, MD_S8VArg(q),
+                   MD_S8VArg(expr_parse.errors.first[0].string));
+        }
+        else{
+            MD_String8 parser_answer = parenthesize(arena, operator_array, expr_parse.node);
+            if(expr_parse.errors.max_message_kind || !MD_S8Match(parser_answer, a, 0)){
+                printf("Example %d : Expected answer for %.*s is %.*s. Got %.*s\n", 
+                       i_test, MD_S8VArg(q), MD_S8VArg(a), MD_S8VArg(parser_answer));
+            }
+        }
+    }
+
+    return 0;
+}