diff --git a/src/HerbGrammar.jl b/src/HerbGrammar.jl
index 5c22fc6..7914c0d 100644
--- a/src/HerbGrammar.jl
+++ b/src/HerbGrammar.jl
@@ -50,6 +50,7 @@ export
     clearconstraints!,
     addconstraint!,
     merge_grammars!,
+    expr2rulenode,
 
     @pcfgrammar,
 
diff --git a/src/rulenode_operators.jl b/src/rulenode_operators.jl
index e9f395b..2774cf0 100644
--- a/src/rulenode_operators.jl
+++ b/src/rulenode_operators.jl
@@ -210,6 +210,176 @@ function _rulenode2expr(typ::Symbol, rulenode::AbstractRuleNode, grammar::Abstra
     retval, j
 end
 
+# ---------------------------------------------
+# expr2rulenode and associated functions
+# ---------------------------------------------
+
+function grammar_map_right_to_left(grammar::AbstractGrammar)
+    tags = Dict{Any,Any}()
+    for (l, r) in zip(grammar.types, grammar.rules)
+        tags[r] = l
+    end
+    return tags
+end
+
+function _expr2rulenode(expr::Expr, grammar::AbstractGrammar, tags::Dict{Any,Any})
+    if expr.head == :call 
+
+        if !haskey(tags, expr)
+       
+            parameters = [_expr2rulenode(expr.args[i], grammar, tags) for i in (2:length(expr.args))]
+            pl = map( x -> x[1], parameters)
+            pr = map( x -> x[2], parameters)
+            
+            temp = [expr.args[1] ;pl]
+            newexpr = Expr(:call, temp...)
+            rule = findfirst(==(newexpr), grammar.rules)
+
+
+            oldpl = copy(pl)
+            oldpr = copy(pr)
+            pnr = length(pl)
+
+            while isnothing(rule)
+                
+                updatedrule = findfirst(==(pl[pnr]), grammar.rules)     
+                
+                if isnothing(updatedrule)
+                    pl[pnr] = oldpl[pnr]
+                    pr[pnr] = oldpr[pnr]
+                    pnr = pnr - 1
+                    continue
+                end
+
+                pl[pnr] = tags[pl[pnr]]
+                pr[pnr] = RuleNode(updatedrule, [pr[pnr]])
+  
+                temp = [expr.args[1] ;pl]
+                newexpr = Expr(:call, temp...)
+                rule = findfirst(==(newexpr), grammar.rules)
+                
+                pnr = length(pl)
+            end
+            return (tags[newexpr], RuleNode(rule, pr))
+        else 
+            rule = findfirst(==(expr), grammar.rules)
+            return (tags[expr], RuleNode(rule, []))
+        end
+    elseif expr.head == :block
+        (l1, r1) = _expr2rulenode( expr.args[1], grammar, tags)
+        (l2, r2) = _expr2rulenode( expr.args[3], grammar, tags)
+        
+        temp = (l1, l2)
+
+        newexpr = Expr(:block, temp...)
+        rule = findfirst(==(newexpr), grammar.rules)
+
+        pl = [l1, l2]
+        pr = [r1, r2]
+
+        oldpl = copy(pl)
+        oldpr = copy(pr)
+        pnr = length(pl)
+
+        while isnothing(rule)
+            
+            updatedrule = findfirst(==(pl[pnr]), grammar.rules)     
+            
+            if isnothing(updatedrule)
+                pl[pnr] = oldpl[pnr]
+                pr[pnr] = oldpr[pnr]
+                pnr = pnr - 1
+                continue
+            end
+            
+            pl[pnr] = tags[pl[pnr]]
+            pr[pnr] = RuleNode(updatedrule, [pr[pnr]])
+            
+            temp = (pl[1], pl[2])
+            newexpr = Expr(:block, temp...)
+            rule = findfirst(==(newexpr), grammar.rules)
+            
+            pnr = length(pl)
+        end
+        return (tags[newexpr], RuleNode(rule, pr))
+        
+    elseif expr.head == :quote
+        return _expr2rulenode(expr.args[1], grammar, tags)
+    else
+        error("Only call and block expressions are supported")
+    end
+end
+
+function _expr2rulenode(expr::Any, grammar::AbstractGrammar, tags::Dict{Any,Any})
+    rule = findfirst(==(expr), grammar.rules)
+    return (tags[expr], RuleNode(rule, []))
+end
+
+"""
+    expr2rulenode(expr::Expr, grammar::AbstractGrammar, startSymbol::Symbol)
+
+Converts an expression into a [`AbstractRuleNode`](@ref) corresponding to the rule definitions in the grammar.
+"""
+function expr2rulenode(expr::Expr, grammar::AbstractGrammar, startSymbol::Symbol)
+    tags = grammar_map_right_to_left(grammar)
+    (s, rn) = _expr2rulenode(expr, grammar, tags)
+    while s != startSymbol
+            
+        updatedrule = findfirst(==(s), grammar.rules)     
+        
+        if isnothing(updatedrule)
+            error("INVALID STARTING SYMBOL")
+        end
+            
+        s = tags[s]
+        rn = RuleNode(updatedrule, [rn])
+    end
+    return rn
+end
+
+"""
+    expr2rulenode(expr::Expr, grammar::AbstractGrammar)
+
+Converts an expression into a [`AbstractRuleNode`](@ref) corresponding to the rule definitions in the grammar.
+"""
+function expr2rulenode(expr::Expr, grammar::AbstractGrammar)
+    tags = grammar_map_right_to_left(grammar)
+    (s, rn) = _expr2rulenode(expr, grammar, tags)
+    return rn
+end
+
+"""
+    expr2rulenode(expr::Symbol, grammar::AbstractGrammar, startSymbol::Symbol)
+
+Converts an expression into a [`AbstractRuleNode`](@ref) corresponding to the rule definitions in the grammar.
+"""
+function expr2rulenode(expr::Symbol, grammar::AbstractGrammar, startSymbol::Symbol)
+    tags = get_tags(grammar)
+    (s, rn) = expr2rulenode(expr, grammar, tags)
+    while s != startSymbol
+            
+        updatedrule = findfirst(==(s), grammar.rules)     
+        
+        if isnothing(updatedrule)
+            error("INVALID STARTING SYMBOL")
+        end
+            
+        s = tags[s]
+        rn = RuleNode(updatedrule, [rn])
+    end
+    return rn
+end
+
+"""
+    expr2rulenode(expr::Symbol, grammar::AbstractGrammar)
+
+Converts an expression into a [`AbstractRuleNode`](@ref) corresponding to the rule definitions in the grammar.
+"""
+function expr2rulenode(expr::Symbol, grammar::AbstractGrammar)
+    tags = get_tags(grammar)
+    (s, rn) = expr2rulenode(expr, grammar, tags)
+    return rn
+end
 
 """
 Calculates the log probability associated with a rulenode in a probabilistic grammar.
diff --git a/test/runtests.jl b/test/runtests.jl
index b26dd0c..1a7221f 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -2,8 +2,10 @@ using HerbCore
 using HerbGrammar
 using Test
 
+
 @testset "HerbGrammar.jl" verbose=true begin
     include("test_csg.jl")
     include("test_rulenode_operators.jl")
     include("test_rulenode2expr.jl")
+    include("test_expr2rulenode.jl")
 end
diff --git a/test/test_expr2rulenode.jl b/test/test_expr2rulenode.jl
new file mode 100644
index 0000000..664313e
--- /dev/null
+++ b/test/test_expr2rulenode.jl
@@ -0,0 +1,47 @@
+@testset verbose=true "expr2rulenode" begin
+
+    g1 = @cfgrammar begin
+    Number = |(1:2)
+    Number = x
+    Number = Number + Number 
+    Number = Number * Number
+    Number = DiffNumber
+    DiffNumber = |(3:4)
+    end
+    
+    expr1 = :(1 + 2)
+    expr2 = :((x * (1 + 3)) + (4 * x))
+    @test expr2rulenode(expr1, g1) == RuleNode(4, [RuleNode(1, []), RuleNode(2, [])])    
+    @test expr2rulenode(expr2, g1) == RuleNode(4, [ RuleNode(5, [RuleNode(3, []), RuleNode(4, [RuleNode(1, []), RuleNode(6,[RuleNode(7, [])])])]), RuleNode(5,[RuleNode(6, [RuleNode(8, [])]), RuleNode(3, [])])])
+
+
+    g2 = @csgrammar begin
+        Start = Sequence                   #1
+    
+        Sequence = Operation                #2
+        Sequence = (Operation; Sequence)    #3
+        Operation = Transformation          #4
+        Operation = ControlStatement        #5
+    
+        Transformation = moveRight() | moveDown() | moveLeft() | moveUp() | drop() | grab()     #6
+        ControlStatement = IF(Condition, Sequence, Sequence)        #12
+        ControlStatement = WHILE(Condition, Sequence)               #13
+    
+        Condition = atTop() | atBottom() | atLeft() | atRight() | notAtTop() | notAtBottom() | notAtLeft() | notAtRight()      #14
+    end
+
+    expr3 = :(moveUp())
+    expr4 = :(moveUp(); (moveRight()))
+    expr5 = :(IF(atTop(), ((moveUp(); (moveRight()))), moveRight()))
+
+    @test expr2rulenode(expr3, g2) == RuleNode(9, [])
+    @test expr2rulenode(expr3, g2, :Start) == RuleNode(1, [RuleNode(2, [RuleNode(4, [RuleNode(9, [])])])])
+
+    @test expr2rulenode(expr4, g2) == RuleNode(3, [RuleNode(4, [RuleNode(9, [])]) , RuleNode(2, [RuleNode(4, [RuleNode(6, [])])])])
+    @test expr2rulenode(expr4, g2, :Start) == RuleNode(1, [RuleNode(3, [RuleNode(4, [RuleNode(9, [])]) , RuleNode(2, [RuleNode(4, [RuleNode(6, [])])])])])
+
+    @test expr2rulenode(expr5, g2) == RuleNode(12, [RuleNode(14, []), RuleNode(3, [RuleNode(4, [RuleNode(9, [])]) , RuleNode(2, [RuleNode(4, [RuleNode(6, [])])])]), RuleNode(2, [RuleNode(4, [RuleNode(6, [])])])])
+    @test expr2rulenode(expr5, g2, :Start) == RuleNode(1, [RuleNode(2, [RuleNode(5, [RuleNode(12, [RuleNode(14, []), RuleNode(3, [RuleNode(4, [RuleNode(9, [])]) , RuleNode(2, [RuleNode(4, [RuleNode(6, [])])])]), RuleNode(2, [RuleNode(4, [RuleNode(6, [])])])])])])])
+    
+end
+