Fixed typos, added more docs. Renamed Local in compiler.nim to a more generic Name. Removed 'raise' from main.nim
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Nocturn9x
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44b52949e4
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8bac5fe657
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@ -30,19 +30,29 @@ export bytecode
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type
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Local = ref object
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Name = ref object
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## A wrapper around declared names.
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## Depth indicates to which scope
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## the variable belongs, zero meaning
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## the global one. Note that all names
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## are resolved statically unless the
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## dynamic specifier is used, hence if
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## the compiler cannot resolve a name
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## at compile-time it will error out even
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## if everything would be fine at runtime
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name: ASTNode
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isStatic: bool
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isPrivate: bool
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depth: int
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Compiler* = ref object
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## A wrapper around the compiler's state
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chunk: Chunk
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ast: seq[ASTNode]
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enclosing: Compiler
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current: int
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file: string
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locals: seq[Local]
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names: seq[Name]
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scopeDepth: int
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currentFunction: FunDecl
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@ -53,11 +63,13 @@ proc initCompiler*(): Compiler =
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result.ast = @[]
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result.current = 0
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result.file = ""
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result.locals = @[]
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result.names = @[]
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result.scopeDepth = 0
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result.currentFunction = nil
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## Forward declarations
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proc expression(self: Compiler, node: ASTNode)
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@ -66,8 +78,8 @@ proc peek(self: Compiler, distance: int = 0): ASTNode =
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## Peeks at the AST node at the given distance.
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## If the distance is out of bounds, the last
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## AST node in the tree is returned. A negative
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## distance may be used to retrieve previously consumed
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## AST nodes
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## distance may be used to retrieve previously
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## consumed AST nodes
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if self.ast.high() == -1 or self.current + distance > self.ast.high() or self.current + distance < 0:
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result = self.ast[^1]
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else:
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@ -81,12 +93,16 @@ proc done(self: Compiler): bool =
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proc check(self: Compiler, kind: NodeKind): bool =
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## Returns if the current node is of the
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## expected kind
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if self.done():
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return false
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return self.peek().kind == kind
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proc check(self: Compiler, kinds: openarray[NodeKind]): bool =
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## Returns if the current node's kind matches any
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## of the given ones. Bails out at the first match
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for kind in kinds:
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if self.check(kind):
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return true
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@ -94,14 +110,16 @@ proc check(self: Compiler, kinds: openarray[NodeKind]): bool =
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proc step(self: Compiler): ASTNode =
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## Steps n nodes into the input,
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## returning the last consumed one
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## Steps to the next node and returns
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## the consumed one
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result = self.peek()
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if not self.done():
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self.current += 1
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proc match(self: Compiler, kind: NodeKind): bool =
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## Same as self.check(), but it calls self.step()
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## internally if self.check() returns true
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if self.check(kind):
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discard self.step()
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return true
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@ -109,6 +127,8 @@ proc match(self: Compiler, kind: NodeKind): bool =
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proc match(self: Compiler, kinds: openarray[NodeKind]): bool =
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## Same as match, but can match more than one node
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## kind at a time
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for kind in kinds:
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if self.match(kind):
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return true
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@ -117,13 +137,13 @@ proc match(self: Compiler, kinds: openarray[NodeKind]): bool =
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proc error(self: Compiler, message: string) =
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## Raises a formatted CompileError exception
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let tok = if not self.done(): self.peek().token else: self.peek(-1).token
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let tok = self.peek().token
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raise newException(CompileError, &"A fatal error occurred while compiling '{self.file}', line {tok.line} at '{tok.lexeme}' -> {message}")
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proc emitByte(self: Compiler, byt: OpCode|uint8) =
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## Emits a single bytecode instruction and writes it
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## to the current chunk being compiled
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## Emits a single byte, writing it to
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## the current chunk being compiled
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when DEBUG_TRACE_COMPILER:
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echo &"DEBUG - Compiler: Emitting {$byt}"
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self.chunk.write(uint8 byt, self.peek().token.line)
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@ -139,7 +159,7 @@ proc emitBytes(self: Compiler, byt1: OpCode|uint8, byt2: OpCode|uint8) =
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proc emitBytes(self: Compiler, bytarr: array[3, uint8]) =
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## Handy helper method to write an array of 3 bytes into
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## the current chunk, calling emiteByte(s) on each of its
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## the current chunk, calling emitByte on each of its
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## elements
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self.emitBytes(bytarr[0], bytarr[1])
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self.emitByte(bytarr[2])
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@ -253,9 +273,9 @@ proc literal(self: Compiler, node: ASTNode) =
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proc unary(self: Compiler, node: UnaryExpr) =
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## Parses unary expressions such as negation or
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## Compiles unary expressions such as negation or
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## bitwise inversion
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self.expression(node.a)
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self.expression(node.a) # Pushes the operand onto the stack
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case node.operator.kind:
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of Minus:
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self.emitByte(UnaryNegate)
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@ -270,6 +290,10 @@ proc unary(self: Compiler, node: UnaryExpr) =
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proc binary(self: Compiler, node: BinaryExpr) =
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## Compiles all binary expressions
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# These two lines prepare the stack by pushing the
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# opcode's operands onto it
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self.expression(node.a)
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self.expression(node.b)
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case node.operator.kind:
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@ -305,12 +329,13 @@ proc binary(self: Compiler, node: BinaryExpr) =
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self.emitByte(BinaryShiftRight)
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of LeftShift:
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self.emitByte(BinaryShiftLeft)
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# TODO: In-place operations
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# TODO: In-place operations (requires variables)
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else:
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self.error(&"invalid AST node of kind {node.kind} at binary(): {node} (This is an internal error and most likely a bug)")
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proc expression(self: Compiler, node: ASTNode) =
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## Compiles all expressions
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case node.kind:
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of unaryExpr:
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self.unary(UnaryExpr(node))
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@ -327,6 +352,7 @@ proc expression(self: Compiler, node: ASTNode) =
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proc statement(self: Compiler, node: ASTNode) =
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## Compiles all statements
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case self.peek().kind:
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of exprStmt:
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self.expression(ExprStmt(node).expression)
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@ -336,6 +362,7 @@ proc statement(self: Compiler, node: ASTNode) =
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proc declaration(self: Compiler, node: ASTNode) =
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## Compiles all declarations
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case node.kind:
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of classDecl, funDecl:
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discard # TODO
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@ -344,10 +371,12 @@ proc declaration(self: Compiler, node: ASTNode) =
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proc compile*(self: Compiler, ast: seq[ASTNode], file: string): Chunk =
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## Compiles a sequence of AST nodes into a chunk
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## object
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self.chunk = newChunk()
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self.ast = ast
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self.file = file
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self.locals = @[]
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self.names = @[]
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self.scopeDepth = 0
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self.currentFunction = nil
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self.current = 0
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@ -355,5 +384,5 @@ proc compile*(self: Compiler, ast: seq[ASTNode], file: string): Chunk =
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self.declaration(self.step())
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if self.ast.len() > 0:
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# *Technically* an empty program is a valid program
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self.emitByte(OpCode.Return) # Exits the VM's main loop
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self.emitByte(OpCode.Return) # Exits the VM's main loop when used at the global scope
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result = self.chunk
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@ -113,7 +113,6 @@ proc main() =
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compileDate = fromUnix(serialized.compileDate).format("d/M/yyyy H:mm:ss")
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echo &"\t\t- Compilation date & time: {compileDate}"
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except:
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raise
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echo &"A Nim runtime exception occurred: {getCurrentExceptionMsg()}"
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continue
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